Lipid depot formulations

ABSTRACT

The present invention relates to pre-formulations comprising low viscosity, non-liquid crystalline, mixtures of:a) at least one neutral diacyl lipid and/or at least one tocopherol;b) at least one phospholipid;c) at least one biocompatible, oxygen containing, low viscosity organic solvent;wherein at least one bioactive agent is dissolved or dispersed in the low viscosity mixture and wherein the pre-formulation forms, or is capable of forming, at least one liquid crystalline phase structure upon contact with an aqueous fluid. The preformulations are suitable for generating parenteral, non-parenteral and topical depot compositions for sustained release of active agents. The invention additionally relates to a method of delivery of an active agent comprising administration of a preformulation of the invention, a method of treatment comprising administration of a preformulation of the invention and the use of a preformulation of the invention in a method for the manufacture of a medicament.

This application is a continuation of application Ser. No. 13/537,096,filed Jun. 29, 2012, now allowed, which is a continuation of applicationSer. No. 11/628,007 filed Jul. 24, 2007, now issued U.S. Pat. No.8,236,292, which in turn is the U.S. national phase ofPCT/GB2005/002217, filed 6 Jun. 2005, which designated the U.S. andclaims priority of GB 0412530.8, filed 4 Jun. 2004; GB 0500807.3, filed14 Jan. 2005 and GB 0507811.8, filed 18 Apr. 2005, the entire contentsof each of which are hereby incorporated by reference in thisapplication.

The present invention relates to formulation precursors(pre-formulations) for the in situ generation of controlled releaselipid compositions. In particular, the invention relates topre-formulations in the form of low viscosity mixtures (such asmolecular solutions) of amphiphilic components and at least onebioactive agent which undergo at least one phase transition uponexposure to aqueous fluids, such as body fluids, thereby forming acontrolled release matrix which optionally is bioadhesive.

Many bioactive agents including pharmaceuticals, nutrients, vitamins andso forth have a “functional window”. That is to say that there is arange of concentrations over which these agents can be observed toprovide some biological effect. Where the concentration in theappropriate part of the body (e.g. locally or as demonstrated by serumconcentration) falls below a certain level, no beneficial effect can beattributed to the agent. Similarly, there is generally an upperconcentration level above which no further benefit is derived byincreasing the concentration. In some cases increasing the concentrationabove a particular level results in undesirable or even dangerouseffects.

Some bioactive agents have a long biological half-life and/or a widefunctional window and thus may be administered occasionally, maintaininga functional biological concentration over a substantial period of time(e.g. 6 hours to several days). In other cases the rate of clearance ishigh and/or the functional window is narrow and thus to maintain abiological concentration within this window regular (or even continuous)doses of a small amount are required. This can be particularly difficultwhere non-oral routes of administration (e.g. parenteral administration)are desirable. Furthermore, in some circumstances, such as in thefitting of implants (e.g. joint replacements or oral implants) the areaof desired action may not remain accessible for repeated administration.In such cases a single administration must provide active agent at atherapeutic level over the whole period during which activity is needed.

Various method have been used and proposed for the sustained release ofbiologically active agents. Such methods include slow-release, orallyadministered compositions, such as coated tablets, formulations designedfor gradual absorption, such as transdermal patches, and slow-releaseimplants such as “sticks” implanted under the skin.

One method by which the gradual release of a bioactive agent has beenproposed is a so-called “depot” injection. In this method, a bioactiveagent is formulated with carriers providing a gradual release of activeagent over a period of a number of hours or days. These are often basedupon a degrading matrix which gradually disperses in the body to releasethe active agent.

The most common of the established methods of depot injection reliesupon a polymeric depot system. This is typically a biodegradable polymersuch poly (lactic acid) (PLA) and/or poly (lactic-co-glycolic acid)(PLGA) and may be in the form of a solution in an organic solvent, apre-polymer mixed with an initiator, encapsulated polymer particles orpolymer microspheres. The polymer or polymer particles entrap the activeagent and are gradually degraded releasing the agent by slow diffusionand/or as the matrix is absorbed. Examples of such systems include thosedescribed in U.S. Pat. No. 4,938,763, U.S. Pat. No. 5,480,656 and U.S.Pat. No. 6,113,943 and can result in delivery of active agents over aperiod of up to several months. These systems do, however, have a numberof limitations including the complexity of manufacturing and difficultyin sterilising (especially the microspheres). The local irritationcaused by the lactic and/or glycolic acid which is released at theinjection site is also a noticeable drawback. There is also often quitea complex procedure to prepare the injection dose from the powderprecursor

From a drug delivery point of view, polymer depot compositions also havethe disadvantage of accepting only relatively low drug loads and havinga “burst/lag” release profile. The nature of the polymeric matrix,especially when applied as a solution or pre-polymer, causes an initialburst of drug release when the composition is first administered. Thisis followed by a period of low release, while the degradation of thematrix begins, followed finally by an increase in the release rate tothe desired sustained profile. This burst/lag release profile can causethe in vivo concentration of active agent to burst above the functionalwindow immediately following administration, then drop back through thebottom of the functional window during the lag period before reaching asustained functional concentration. Evidently, from a functional andtoxicological point of view this burst/lag release profile isundesirable and could be dangerous. It may also limit the equilibriumconcentration which can be provided due to the danger of adverse effectsat the “peak” point.

Previous depot systems have been sought to address the problem of burstrelease. In particular, the use of hydrolysed polylactic acid and theinclusion of poly lactic acid-polyethylene glycol block copolymers havebeen proposed to provide the “low burst” polymeric system described inU.S. Pat. No. 6,113,943 and U.S. Pat. No. 6,630,115. These systemsprovide improved profiles but the burst/lag effect remains and they donot address other issues such as the irritation caused by the use ofpolymers producing acidic degradation products.

One alternative to the more established, polymer based, depot systemswas proposed in U.S. Pat. No. 5,807,573. This proposes a lipid basedsystem of a diacylglycerol, a phospolipid and optionally water,glycerol, ethylene glycol or propylene glycol to provide anadministration system in the reversed micellar “L2” phase or a cubicliquid crystalline phase. Since this depot system is formed fromphysiologically well tolerated diacyl glycerols and phospholipids, anddoes not produce the lactic acid or glycolic acid degradation productsof the polymeric systems, there is less tendency for this system toproduce inflammation at the injection site. The liquid crystallinephases are, however, of high viscosity and the L2 phase may also be tooviscous for ease of application. The authors of U.S. Pat. No. 5,807,573also do not provide any in vivo assessment of the release profile of theformulation and thus it is uncertain whether or not a “burst” profile isprovided.

The use of non-lamellar phase structures (such as liquid crystallinephases) in the delivery of bioactive agents is now relatively wellestablished. Such structures form when an amphiphilic compound isexposed to a solvent because the amphiphile has both polar and apolargroups which cluster to form polar and apolar regions. These regions caneffectively solubilise both polar and apolar compounds. In addition,many of the structures formed by amphiphiles in polar and/or apolarsolvents have a very considerable area of polar/apolar boundary at whichother amphiphilic compounds can be adsorbed and stabilised. Amphiphilescan also be formulated to protect active agents, to at least someextent, from aggressive biological environments, including enzymes, andthereby provide advantageous control over active agent stability andrelease.

The formation of non-lamellar regions in the amphiphile/water,amphiphile/oil and amphiphile/oil/water phase diagrams is a well knownphenomenon. Such phases include liquid crystalline phases such as thecubic P, cubic D, cubic G and hexagonal phases, which are fluid at themolecular level but show significant long-range order, and the L3 phasewhich comprises a multiply interconnected bi-continuous network ofbilayer sheets which are non-lamellar but lack the long-range order ofthe liquid crystalline phases. Depending upon their curvature of theamphiphile sheets, these phases may be described as normal (meancurvature towards the apolar region) or reversed (mean curvature towardsthe polar region).

The non-lamellar liquid crystalline and L3 phases are thermodynamicallystable systems. That is to say, they are not simply a meta-stable statethat will separate and/or reform into layers, lamellar phases or thelike, but are the stable thermodynamic form of the lipid/solventmixture.

While the effectiveness of known lipid depot formulations is high, thereare certain aspects in which the performance of these is less thanideal. In particular, cubic liquid crystalline phases proposed arerelatively viscous in nature. This makes application with a standardsyringe difficult, and possibly painful to the patient, and makessterilisation by filtration impossible because the composition cannot bepassed through the necessary fine-pored membrane. As a result, thecompositions must be prepared under highly sterile conditions, whichadds to the complexity of manufacturing. Where L2 phases are used, theseare generally of lower viscosity but these may still cause difficulty inapplication and allow access to only a small region of the phasediagram. Specifically, the solvents used in known lipid formulationshave only a limited effect in reducing the viscosity of the mixture.Water, for example, will induce the formation of a highly viscous liquidcrystalline phase and solvents such as glycerol and glycols have a highviscosity and do not provide any greatly advantageous decrease in theviscosity of the composition. Glycols are also typically toxic or poorlytolerated in vivo and can cause irritation when applied topically.

Furthermore, the known lipid compositions in the low-solvent L2 phasemay support only a relatively low level of many bioactive agents becauseof their limited solubility in the components of the mixture in theabsence of water. In the presence of water, however, the formulationsadopt a highly viscous cubic liquid crystalline phase. It would be aclear advantage to provide a depot system that could be injected at lowviscosity and allowed release of the required concentration of bioactivewith a smaller depot composition volume.

The known lipid depot compositions also have practical access to onlycertain phase structures and compositions because other mixtures areeither too highly viscous for administration (such as those with highphospholipid concentrations) or run the risk of separation into two ormore separate phases (such as an L2 phase in equilibrium with a phaserich in phospholipid). In particular, phospholipid concentrations above50% are not reachable by known methods and from the phase diagram shownin U.S. Pat. No. 5,807,573 it appears that the desired cubic phase isstable at no higher than 40% phospholipid. As a result, it has not beenpossible in practice to provide depot compositions of high phospholipidconcentration or having a hexagonal liquid crystalline phase structure.

The present inventors have now established that by providing apre-formulation comprising certain amphiphilic components, at least onebioactive agent and a biologically tolerable solvent, especially in alow viscosity phase such as molecular solution, the pre-formulation maybe generated addressing many of the shortfalls of previous depotformulations. In particular, the pre-formulation is easy to manufacture,may be sterile-filtered, it has low viscosity (allowing easy and lesspainful administration), allows a high level of bioactive agent to beincorporated (thus allowing a smaller amount of composition to be used)and/or forms a desired non-lamellar depot composition in vivo having acontrollable “burst” or “non-burst” release profile. The compositionsare also formed from materials that are non-toxic, biotolerable andbiodegradable. Furthermore, the pre-formulation is suitable for theformation of depot compositions following parenteral administration andalso following non-parenteral (e.g. topical) administration to bodycavities and/or surfaces of the body or elsewhere.

In a first aspect, the present invention thus provides a pre-formulationcomprising a low viscosity mixture of:

a) at least one neutral diacyl lipid and/or a tocopherol;

b) at least one phospholipid;

c) at least one biocompatible, (preferably oxygen containing) organicsolvent;

wherein at least one bioactive agent is dissolved or dispersed in thelow viscosity mixture and wherein the pre-formulation forms, or iscapable of forming, at least one liquid crystalline phase structure uponcontact with an aqueous fluid.

Generally, the aqueous fluid will be a body fluid such as fluid from amucosal surface, tears, sweat, saliva, gastro-intestinal fluid,extra-vascular fluid, extracellular fluid, interstitial fluid or plasma,and the pre-formulation will form a liquid crystalline phase structurewhen contacted with a body surface, area or cavity (e.g. in vivo) uponcontact with the aqueous body fluid. The pre-formulation of theinvention will generally not contain any significant quantity of waterprior to administration.

In a second aspect of the invention, there is also provided a method ofdelivery of a bioactive agent to a human or non-human animal (preferablymammalian) body, this method comprising administering (preferablyparenterally) a pre-formulation comprising a low viscosity mixture of:

a) at least one neutral diacyl lipid and/or a tocopherol;

b) at least one phospholipid;

c) at least one biocompatible, (preferably oxygen containing) organicsolvent;

and at least one bioactive agent is dissolved or dispersed in the lowviscosity mixture, whereby to form at least one liquid crystalline phasestructure upon contact with an aqueous fluid in vivo followingadministration. Preferably, the pre-formulation administered in such amethod is a pre-formulation of the invention as described herein.

The method of administration suitable for the above method of theinvention will be a method appropriate for the condition to be treatedand the bioactive agent used. A parenteral depot will thus be formed byparenteral (e.g. subcutaneous or intramuscular) administration while abioadhesive non-parenteral (e.g. topical) depot composition may beformed by administration to the surface of skin, mucous membranes and/ornails, to opthalmological, nasal, oral or internal surfaces or tocavities such as nasal, rectal, vaginal or buccal cavities, theperiodontal pocket or cavities formed following extraction of a naturalor implanted structure or prior to insertion of an implant (e.g a joint,stent, cosmetic implant, tooth, tooth filling or other implant).

In a further aspect, the present invention also provides a method forthe preparation of a liquid crystalline composition (especially a depotcomposition) comprising exposing a pre-formulation comprising a lowviscosity mixture of:

a) at least one neutral diacyl lipid and/or a tocopherol;

b) at least one phospholipid;

c) at least one biocompatible (preferably oxygen containing), organicsolvent;

and at least one bioactive agent dissolved or dispersed in the lowviscosity mixture, to an aqueous fluid (particularly in vivo and/orparticularly a body fluid as indicated herein). Preferably thepre-formulation administered is a pre-formulation of the presentinvention as described herein. The exposure to a fluid “in vivo” mayevidently be internally within the body or a body cavity, or may be at abody surface such as a skin surface, depending upon the nature of thecomposition.

The liquid crystalline composition formed in this method is preferablybioadhesive as described herein.

In a still further aspect the present invention provides a process forthe formation of a pre-formulation suitable for the administration of abioactive agent to a (preferably mammalian) subject, said processcomprising forming a low viscosity mixture of a) at least one neutraldiacyl lipid and/or a tocopherol;

b) at least one phospholipid;

c) at least one biocompatible (preferably oxygen containing), organicsolvent;

and dissolving or dispersing at least one bioactive agent in the lowviscosity mixture, or in at least one of components a, b or c prior toforming the low viscosity mixture. Preferably the pre-formulationso-formed is a formulation of the invention as described herein.

In a yet still further aspect the present invention provides the use ofa low viscosity mixture of:

a) at least one neutral diacyl lipid and/or a tocopherol;

b) at least one phospholipid;

c) at least one biocompatible (preferably oxygen containing), organicsolvent;

wherein at least one bioactive agent is dissolved or dispersed in thelow viscosity mixture in the manufacture of a pre-formulation for use inthe sustained administration of said active agent, wherein saidpre-formulation is capable of forming at least one liquid crystallinephase structure upon contact with an aqueous fluid.

As used herein, the term “low viscosity mixture” is used to indicate amixture which may be readily administered to a subject and in particularreadily administered by means of a standard syringe and needlearrangement. This may be indicated, for example by the ability to bedispensed from a 1 ml disposable syringe through a 22 awg (or a 23gauge) needle by manual pressure. In a particularly preferredembodiment, the low viscosity mixture should be a mixture capable ofpassing through a standard sterile filtration membrane such as a 0.22 μmsyringe filter. In other preferred embodiments, a similar functionaldefinition of a suitable viscosity can be defined as the viscosity of apre-formulation that can be sprayed using a compression pump orpressurized spray device using conventional spray equipment. A typicalrange of suitable viscosities would be, for example, 0.1 to 5000 mPas,preferably 1 to 1000 mPas at 20° C.

It has been observed that by the addition of small amounts of lowviscosity solvent, as indicated herein, a very significant change inviscosity can be provided. As indicated in FIG. 2, for example, theaddition of only 5% solvent can reduce viscosity 100-fold and additionof 10% may reduce the viscosity up to 10,000 fold. In order to achievethis non-linear, synergistic effect, in lowering viscosity it isimportant that a solvent of appropriately low viscosity and suitablepolarity be employed. Such solvents include those described hereininfra.

Particularly preferred examples of low viscosity mixtures are molecularsolutions and/or isotropic phases such as L2 and/or L3 phases. Asdescribe above, the L3 is a non-lamellar phase of interconnected sheetswhich has some phase structure but lacks the long-range order of aliquid crystalline phase. Unlike liquid crystalline phases, which aregenerally highly viscous, L3 phases are of lower viscosity.

Obviously, mixtures of L3 phase and molecular solution and/or particlesof L3 phase suspended in a bulk molecular solution of one or morecomponents are also suitable. The L2 phase is the so-called “reversedmicellar” phase or microemulsion. Most preferred low viscosity mixturesare molecular solutions, L3 phases and mixtures thereof. L2 phases areless preferred, except in the case of swollen L2 phases as describedbelow.

The present invention provides a pre-formulation comprising componentsa, b, c and at least one bioactive agent as indicated herein. One of theconsiderable advantages of the pre-formulations of the invention is thatcomponents a and b may be formulated in a wide range of proportions. Inparticular, it is possible to prepare and use pre-formulations of thepresent invention having a much greater proportion of phospholipid toneutral, diacyl lipid and/or tocopherol than was previously achievablewithout risking phase separation and/or unacceptably high viscosities inthe pre-formulation. The weight ratios of components a:b may thus beanything from 5:95 right up to 95:5. Preferred ratios would generally befrom 90:10 to 20:80 and more preferably from 85:15 to 30:70. In onepreferred embodiment of the invention, there is a greater proportion ofcomponent b than component a. That is, the weight ratio a:b is below50:50, e.g. 48:52 to 2:98, preferably, 40:60 to 10:90 and morepreferably 35:65 to 20:80.

The amount of component c in the pre-formulations of the invention willbe at least sufficient to provide a low viscosity mixture (e.g. amolecular solution, see above) of components a, b and c and will beeasily determined for any particular combination of components bystandard methods. The phase behaviour itself may be analysed bytechniques such as visual observation in combination with polarizedlight microscopy, nuclear magnetic resonance, and cryo-transmissionelectron microscopy (cryo-TEM) to look for solutions, L2 or L3 phases,or liquid crystalline phases. Viscosity may be measured directly bystandard means. As described above, an appropriate practical viscosityis that which can effectively be syringed and particularly sterilefiltered. This will be assessed easily as indicated herein. The maximumamount of component c to be included will depend upon the exactapplication of the pre-formulation but generally the desired propertieswill be provided by any amount forming a low viscosity mixture (e.g. amolecular solution, see above) and/or a solution with sufficiently lowviscosity. Since the administration of unnecessarily large amounts ofsolvent to a subject is generally undesirable the amount of component cwill typically be limited to no more than ten times (e.g. three times)the minimum amount required to form a low viscosity mixture, preferablyno more than five times and most preferably no more than twice thisamount. The composition of the present invention may, however, contain agreater quantity of solvent than would be acceptable in an immediatedosage composition. This is because the process by which the activeagents are slowly released (e.g. formation of shells of liquidcrystalline phase se described herein) also serve to retard the passageof solvent from the composition. As a result, the solvent is releasedover some time (e.g. minutes or hours) rather than instantaneously andso can be better tolerated by the body.

Higher proportions of solvent may also be used for non-parenteral (e.g.topical) applications, especially to body surfaces, where the solventwill be lost by evaporation rather than absorbed into the body. For suchapplications up to 100 times the minimum amount of solvent may be used(e.g. up to 95% by weight of the composition, preferably up to 80% byweight and more preferably up to 50% by weight), especially where a verythin layer of the resulting non-parenteral depot is desired.

Where the compositions of the invention are formulated as(non-parenteral) aerosol spray compositions (e.g. for topical orsystemic delivery of an active), the composition may also comprise apropellant. Such compositions may also include a high proportion ofsolvent component c), as considered above, since much of the solventwill evaporate when the composition is dispensed.

Suitable propellants are volatile compounds which will mix with thecomposition of the invention under the pressure of the spray dispenser,without generating high viscosity mixtures. They should evidently haveacceptable biocompatibility.

Suitable propellants will readily be identified by simple testing andexamples include hydrocarbons (especially C₁ to C₄ hydrocarbons), carbondioxide and nitrogen. Volatile hydrofluorocarbons such as HFCs 134,134a, 227ea and/or 152a may also be suitable.

As a general guide, the weight of component c will typically be around0.5 to 50% of the total weight of the a-b-c solution. This proportion ispreferably (especially for injectable depots) 2 to 30% and morepreferably 5 to 20% by weight.

Component “a” as indicated herein is a neutral lipid componentcomprising a polar “head” group and also non-polar “tail” groups.Generally the head and tail portions of the lipid will be joined by anester moiety but this attachment may be by means of an ether, an amide,a carbon-carbon bond or other attachment. Preferred polar head groupsare non-ionic and include polyols such as glycerol, diglycerol and sugarmoieties (such as inositol and glucosyl based moieties); and esters ofpolyols, such as acetate or succinate esters. Preferred polar groups areglycerol and diglycerol, especially glycerol.

In one preferred aspect, component a is a diacyl lipid in that it hastwo non-polar “tail” groups. This is generally preferable to the use ofmono-acyl (“lyso”) lipids because these are typically less welltolerated in vivo. The two non-polar groups may have the same or adiffering number of carbon atoms and may each independently be saturatedor unsaturated. Examples of non-polar groups include C₆-C₃₂ alkyl andalkenyl groups, which are typically present as the esters of long chaincarboxylic acids. These are often described by reference to the numberof carbon atoms and the number of unsaturations in the carbon chain.Thus, CX:Z indicates a hydrocarbon chain having X carbon atoms and Zunsaturations. Examples particularly include caproyl (C6:0), capryloyl(C8:0), capryl (C10:0), lauroyl (C12:0), myristoyl (C14:0), palmitoyl(C16:0), phytanoly (C16:0), palmitoleoyl (C16:1), stearoyl (C18:0),oleoyl (C18:1), elaidoyl (C18:1), linoleoyl (C18:2), linolenoyl (C18:3),arachidonoyl (C20:4), behenoyl (C22:0) and lignoceroyl (C24:9) groups.Thus, typical non-polar chains are based on the fatty acids of naturalester lipids, including caproic, caprylic, capric, lauric, myristic,palmitic, phytanic, palmitolic, stearic, oleic, elaidic, linoleic,linolenic, arachidonic, behenic or lignoceric acids, or thecorresponding alcohols. Preferable non-polar chains are palmitic,stearic, oleic and linoleic acids, particularly oleic acid.

The diacyl lipid, when used as all or part of component “a”, may besynthetic or may be derived from a purified and/or chemically modifiednatural sources such as vegetable oils. Mixtures of any number of diacyllipids may be used as component a. Most preferably this component willinclude at least a portion of diacyl glycerol (DAG), especially glyceroldioleate (GDO). In one favoured embodiment, component a consists ofDAGs. These may be a single DAG or a mixture of DAGs. A highly preferredexample is DAG comprising at least 50%, preferably at least 80% and evencomprising substantially 100% GDO.

An alternative or additional highly preferred class of compounds for useas all or part of component a are tocopherols. As used herein, the term“a tocopherol” is used to indicate the non-ionic lipid tocopherol, oftenknown as vitamin E, and/or any suitable salts and/or analogues thereof.Suitable analogues will be those providing the phase-behaviour, lack oftoxicity, and phase change upon exposure to aqueous fluids, whichcharacterise the compositions of the present invention. Such analogueswill generally not form liquid crystalline phase structures as a purecompound in water. The most preferred of the tocopherols is tocopherolitself, having the structure below. Evidently, particularly where thisis purified from a natural source, there may be a small proportion ofnon-tocopherol “contaminant” but this will not be sufficient to alterthe advantageous phase-behaviour or lack of toxicity. Typically, atocopherol will contain no more than 10% of non-tocopherol-analoguecompounds, preferably no more than 5% and most preferably no more than2% by weight.

In a further advantageous embodiment of the invention, component a)consists essentially of tocopherols, in particular tocopherol as shownabove.

A preferred combination of constituents for component a) is a mixture ofat least one DAG (e.g. GDO) with at least one tocopherol. Such mixturesinclude 2:98 to 98:2 by weight tocopherol:GDO, e.g. 10:90 to 90:10tocopherol:GDO and especially 20:80 to 80:20 of these compounds. Similarmixtures of tocopherol with other DAGs are also suitable.

Component “b” in the present invention is at least one phospholipid. Aswith component a, this component comprises a polar head group and atleast one non-polar tail group. The difference between components a andb lies principally in the polar group. The non-polar portions may thussuitably be derived from the fatty acids or corresponding alcoholsconsidered above for component a. It will typically be the case that thephospholipid will contain two non-polar groups, although one or moreconstituents of this component may have one non-polar moiety. Where morethan one non-polar group is present these may be the same or different.

Preferred phospholipid polar “head” groups include phosphatidylcholine,phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol.Most preferred is phosphatidylcholine (PC). In a preferred embodiment,component b) thus consists of at least 50% PC, preferably at least 70%PC and most preferably at least 80% PC. Component b) may consistessentially of PC.

The phospholipid portion, even more suitably than any diacyl lipidportion, may be derived from a natural source. Suitable sources ofphospholipids include egg, heart (e.g. bovine), brain, liver (e.g.bovine) and plant sources including soybean. Such sources may provideone or more constituents of component b, which may comprise any mixtureof phospholipids.

Since the pre-formulations of the invention are to be administered to asubject for the controlled release of an active agent, it is preferablethat the components a and b are biocompatible. In this regard, it ispreferable to use, for example, diacyl lipids and phospholipids ratherthan mono-acyl (lyso) compounds. A notable exception to this istocopherol, as described above. Although having only one alkyl chain,this is not a “lyso” lipid in the convention sense. The nature oftocopherol as a well tolerated essential vitamin evidently makes ithighly suitable in biocompatibility.

It is furthermore most preferable that the lipids and phospholipids ofcomponents a and b are naturally occurring (whether they are derivedfrom a natural source or are of synthetic origin). Naturally occurringlipids tend to cause lesser amounts of inflammation and reaction fromthe body of the subject. Not only is this more comfortable for thesubject but it may increase the residence time of the resulting depotcomposition, especially for parenteral depots, since less immune systemactivity is recruited to the administration site. In certain cases itmay, however, be desirable to include a portion of anon-naturally-occurring lipid in components a and/or b. This might be,for example an “ether lipid” in which the head and tail groups arejoined by an ether bond rather than an ester. Suchnon-naturally-occurring lipids may be used, for example, to alter therate of degradation of the resulting depot-composition by having agreater or lesser solubility or vulnerability to breakdown mechanismspresent at the site of active agent release. Although all proportionsfall within the scope of the present invention, generally, at least 50%of each of components a and b will be naturally occurring lipids. Thiswill preferably be at least 75% and may be up to substantially 100%.

Two particularly preferred combinations of components a and b are GDOwith PC and tocopherol with PC, especially in the region 30-90 wt %GDO/tocopherol, 10-60 wt % PC and 1-30% solvent (especially ethanol, NMPand/or ispropanol).

In addition to amphiphilic components a and b, the pre-formulations ofthe invention may also contain additional amphiphilic components atrelatively low levels. In one embodiment of the invention, thepre-formulation contains up to 10% (by weight of components a and b) ofa charged amphiphile, particularly an anionic amphiphile such as a fattyacid. Preferred fatty acids for this purpose include caproic, caprylic,capric, lauric, myristic, palmitic, phytanic, palmitolic, stearic,oleic, elaidic, linoleic, linolenic, arachidonic, behenic or lignocericacids, or the corresponding alcohols. Preferable fatty acids arepalmitic, stearic, oleic and linoleic acids, particularly oleic acid. Itis particularly advantageous that this component be used in combinationwith a cationic peptide active agent (see below). The combination of ananionic lipid and a cationic peptide is believed to provide a sustainedrelease composition of particular value. This may in part be due toincreased protection of the peptide from the degradative enzymes presentin vivo.

Component “c” of the pre-formulations of the invention is an oxygencontaining organic solvent. Since the pre-formulation is to generate adepot composition following administration (e.g. in vivo), upon contactwith an aqueous fluid, it is desirable that this solvent be tolerable tothe subject and be capable of mixing with the aqueous fluid, and/ordiffusing or dissolving out of the pre-formulation into the aqueousfluid. Solvents having at least moderate water solubility are thuspreferred.

In a preferred version, the solvent is such that a relatively smalladdition to the composition comprising a and b, i.e. below 20%, or morepreferably below 10%, give a large viscosity reductions of one order ofmagnitude or more. As described herein, the addition of 10% solvent cangive a reduction of two, three or even four orders of magnitude inviscosity over the solvent-free composition, even if that composition isa solution or L2 phase containing no solvent, or an unsuitable solventsuch as water (subject to the special case considered below), orglycerol.

Typical solvents suitable for use as component c include at least onesolvent selected from alcohols, ketones, esters (including lactones),ethers, amides and sulphoxides.

Examples of suitable alcohols include ethanol, isopropanol and glycerolformal. Monools are preferred to diols and polyols. Where diols orpolyols are used, this is preferably in combination with an at leastequal amount of monool or other preferred solvent. Examples of ketonesinclude acetone, n-methyl pyrrolidone (NMP), 2-pyrrolidone, andpropylene carbonate. Suitable ethers include diethylether, glycofurol,diethylene glycol monoethyl ether, dimethylisobarbide, and polyethyleneglycols. Suitable esters include ethyl acetate and isopropyl acetate anddimethyl sulphide is as suitable sulphide solvent. Suitable amides andsulphoxides include dimethylacetamide (DMA) and dimethylsulphoxide(DMSO), respectively. Less preferred solvents include dimethylisosorbide, tetrahydrofurfuryl alcohol, diglyme and ethyl lactate.

Since the pre-formulations are to be administered to a living subject,it is necessary that the solvent component c is sufficientlybiocompatible. The degree of this biocompatibility will depend upon theapplication method and since component c may be any mixture of solvents,a certain amount of a solvent that would not be acceptable in largequantities may evidently be present. Overall, however, the solvent ormixture forming component c must not provoke unacceptable reactions fromthe subject upon administration. Generally such solvents will behydrocarbons or preferably oxygen containing hydrocarbons, bothoptionally with other substituents such as nitrogen containing groups.It is preferable that little or none of component c contains halogensubstituted hydrocarbons since these tend to have lowerbiocompatibility. Where a portion of halogenated solvent such asdichloromethane or chloroform is necessary, this proportion willgenerally be minimised. Where the depot composition is to be formednon-parenterally a greater range of solvents may evidently be used thanwhere the depot is to be parenteral.

Component c as used herein may be a single solvent or a mixture ofsuitable solvents but will generally be of low viscosity. This isimportant because one of the key aspects of the present invention isthat it provides preformulations that are of low viscosity and a primaryrole of a suitable solvent is to reduce this viscosity. This reductionwill be a combination of the effect of the lower viscosity of thesolvent and the effect of the molecular interactions between solvent andlipid composition. One observation of the present inventors is that theoxygen-containing solvents of low viscosity described herein have highlyadvantageous and unexpected molecular interactions with the lipid partsof the composition, thereby providing a non-linear reduction inviscosity with the addition of a small volume of solvent.

The viscosity of the “low viscosity” solvent component c (single solventor mixture) should typically be no more than 18 mPas at 20° C. This ispreferably no more than mPas, more preferably no more than 10 mPas andmost preferably no more than 7 mPas at 20° C.

The solvent component c will generally be at least partially lost uponin vivo formation of the depot composition, or diluted by absorption ofwater from the surrounding air and/or tissue. It is preferable,therefore, that component c be at least to some extent water miscibleand/or dispersible and at least should not repel water to the extentthat water absorption is prevented. In this respect also, oxygencontaining solvents with relatively small numbers of carbon atoms (forexample up to 10 carbons, preferably up to 8 carbons) are preferred.Obviously, where more oxygens are present a solvent will tend to remainsoluble in water with a larger number of carbon atoms. The carbon toheteroatom (e.g. N, O, preferably oxygen) ratio will thus often bearound 1:1 to 6:1, preferably 2:1 to 4:1. Where a solvent with a ratiooutside one of these preferred ranges is used then this will preferablybe no more than 75%, preferably no more than 50%, in combination with apreferred solvent (such as ethanol). This may be used, for example todecrease the rate of evaporation of the solvent from the pre-formulationin order to control the rate of liquid crystalline depot formation.

A further advantage of the present pre-formulations is that a higherlevel of bioactive agent may be incorporated into the system. Inparticular, by appropriate choice of components a-c (especially c), highlevels of active agent may be dissolved or suspended in thepre-formulations. Generally, the lipid components in the absence ofwater are relatively poorly solubilising but in the presence of waterform phases too viscous to administer easily. Higher proportions ofbioactive agent may be included by use of appropriate solvents ascomponent c and this level will either dissolve in the depot compositionas it forms in situ or may form microdrops or microcrystals which willgradually dissolve and release active agent. A suitable choice ofsolvent will be possible by routine experimentation within theguidelines presented herein.

The pre-formulations of the present invention typically do not containsignificant amounts of water. Since it is essentially impossible toremove every trace of water from a lipid composition, this is to betaken as indicating that only such minimal trace of water exists ascannot readily be removed. Such an amount will generally be less than 1%by weight, preferably less that 0.5% by the weight of thepre-formulation. In one preferred aspect, the pre-formulations of theinvention do not contain glycerol, ethylene glycol or propylene glycoland contain no more than a trace of water, as just described.

There is, however, a certain embodiment of the present invention inwhich higher proportions of water may be tolerated. This is where wateris present as a part of the solvent component in combination with anadditional water-miscible component c (single solvent or mixture). Inthis embodiment, up to 10 wt % water may be present providing that atleast 3 wt %, preferably at least 5% and more preferably at least 7 wt %component c is also present, that component c is water miscible, andthat the resulting preformulation remains non-viscous and thus does notform a liquid crystalline phase. Generally there will be a greateramount of component c) by weight than the weight of water included inthe preformulation. Most suitable solvents of use with water in thisaspect of the invention include ethanol, isopropyl alcohol, NMP, acetoneand ethyl acetate.

The pre-formulations of the present invention contain one or morebioactive agents (described equivalently as “active agents” herein).Active agents may be any compound having a desired biological orphysiological effect, such as a protein, drug, antigen, nutrient,cosmetic, fragrance, flavouring, diagnostic, pharmaceutical, vitamin, ordietary agent and will be formulated at a level sufficient to provide anin vivo concentration at a functional level (including localconcentrations for topical compositions). Under some circumstances oneor more of components a, b and/or c may also be an active agent,although it is preferred that the active agent should not be one ofthese components. Most preferred active agents are pharmaceutical agentsincluding drugs, vaccines, and diagnostic agents.

Drug agents that may be delivered by the present invention include drugswhich act on cells and receptors, peripheral nerves, adrenergicreceptors, cholinergic receptors, the skeletal muscles, thecardiovascular system, smooth muscles, the blood circulation system,endocrine and hormone system, blood circulatory system, synoptic sites,neuroeffector junctional sites, the immunological system, thereproductive system, the skeletal system, autacoid system, thealimentary and excretory systems, the histamine system, and the centralnervous system.

Examples of drugs which may be delivered by the composition of thepresent invention include, but are not limited to, antibacterial agentssuch as β-lactams or macrocyclic peptide antibiotics, anti fungal agentssuch as polyene macrolides (e.g. amphotericin B) or azole antifungals,anticancer and/or anti viral drugs such as nucleoside analogues,paclitaxel and derivatives thereof, anti inflammatorys, such asnon-steroidal anti inflammatory drugs and corticosteroids,cardiovascular drugs including cholesterol lowering and blood-pressurelowing agents, analgesics, antipsychotics and antidepressants includingseritonin uptake inhibitors, prostaglandins and derivatives, vaccines,and bone modulators. Diagnostic agents include radionuclide labelledcompounds and contrast agents including X-ray, ultrasound and MRIcontrast enhancing agents. Nutrients include vitamins, coenzymes,dietary supplements etc.

Particularly suitable active agents include those which would normallyhave a short residence time in the body due to rapid breakdown orexcretion and those with poor oral bioavailability. These includepeptide, protein and nucleic acid based active agents, hormones andother naturally occurring agents in their native or modified forms. Byadministering such agents in the form of a depot composition formed fromthe pre-formulation of the present invention, the agents are provided ata sustained level for a length of time which may stretch to days, weeksor even several months in spite of having rapid clearance rates. Thisoffers obvious advantages in terms of stability and patient complianceover dosing multiple times each day for the same period. In onepreferred embodiment, the active agent thus has a biological half life(upon entry into the blood stream) of less than 1 day, preferably lessthan 12 hours and more preferably less than 6 hours. In some cases thismay be as low as 1-3 hours or less. Suitable agents are also those withpoor oral bioavailability relative to that achieved by injection, forwhere the active agent also or alternatively has a bioavailability ofbelow 0.1%, especially below 0.05% in oral formulations.

Peptide and protein based active agents include human and veterinarydrugs selected from the group consisting of adrenocorticotropic hormone(ACTH) and its fragments, angiotensin and its related peptides,antibodies and their fragments, antigens and their fragments, atrialnatriuretic peptides, bioadhesive peptides, Bradykinins and theirrelated peptides, calcitonins and their related peptides, cell surfacereceptor protein fragments, chemotactic peptides, cyclosporins,cytokines, Dynorphins and their related peptides, endorphins andP-lidotropin fragments, enkephalin and their related proteins, enzymeinhibitors, immunostimulating peptides and polyaminoacids, fibronectinfragments and their related peptides, gastrointestinal peptides,gonadotrophin-releasing hormone (GnRH) agonists and antagonist,glucagons like peptides, growth hormone releasing peptides,immunostimulating peptides, insulins and insulin-like growth factors,interleukins, luthenizing hormone releasing hormones (LHRH) and theirrelated peptides, melanocyte stimulating hormones and their relatedpeptides, nuclear localization signal related peptides, neurotensins andtheir related peptides, neurotransmitter peptides, opioid peptides,oxytocins, vasopressins and their related peptides, parathyroid hormoneand its fragments, protein kinases and their related peptides,somatostatins and their related peptides, substance P and its relatedpeptides, transforming growth factors (TGF) and their related peptides,tumor necrosis factor fragments, toxins and toxoids and functionalpeptides such as anticancer peptides including angiostatins,antihypertension peptides, anti-blood clotting peptides, andantimicrobial peptides; selected from the group consisting of proteinssuch as immunoglobulins, angiogenins, bone morphogenic proteins,chemokines, colony stimulating factors (CSF), cytokines, growth factors,interferons (Type I and II), interleukins, leptins, leukaemia inhibitoryfactors, stem cell factors, transforming growth factors and tumornecrosis factors.

A further considerable advantage of the depot compositions of thepresent invention is that active agents are released gradually over longperiods without the need for repeated dosing. The composition are thushighly suitable for situations where patient compliance is difficult,unreliable or where a level dosage is highly important, such asmood-altering actives, those actives with a narrow therapeutic window,and those administered to children or to people who's lifestyle isincompatible with a reliable dosing regime. Also for “lifestyle” activeswhere the inconvenience of repeated dosing might outweigh the benefit ofthe active. Particular classes of actives for which this aspect offers aparticular advantage include contraceptives, hormones includingcontraceptive hormones, and particularly hormones used in children suchas growth hormone, anti-addictive agents, supplements such as vitamin ormineral supplements, anti-depressants and anticonvulsants

Cationic peptides are particularly suitable for use where a portion ofthe pre-formulation comprises an anionic amphiphile such as a fattyacid. In this embodiment, preferred peptides include octreotide,lanreotide, calcitonin, oxytocin, interferon-beta and -gamma,interleukins 4, 5, 7 and 8 and other peptides having an isoelectricpoint above pH 7, especially above pH 8.

In one preferred aspect of the present invention, the composition of theinvention is such that an I₂ phase, or a mixed phase including I₂ phaseis formed upon exposure to aqueous fluids and a polar active agent isincluded in the composition. Particularly suitable polar active agentsinclude peptide and protein actives, oligo nucleotides, and small watersoluble actives, including those listed above. Of particular interest inthis aspect are the peptide octreotide and other somatostatin relatedpeptides, interferons alpha and beta, glucagon-like peptides 1 and 2,luprorelin and other GnRH agonist, abarelix and other GnRH antagonists,interferon alpha and beta, zolendronate and ibandronate and otherbisphosponates, and polar active chlorhexidine (e.g. chlorhexidinedigluconate or chlorhexidine dihydroch oride).

A particular advantage of the present invention when used in combinationwith protein/peptide active agents is that aggregation of the activeagent is suppressed. In one preferred embodiment, the present inventionthus provides a depot precursor and particularly a depot composition asdescribed herein comprising at least one peptide (e.g. antibody) orprotein active agent wherein no more than 5% of the active agent is inaggregated form. Preferably no more than 3% is aggregated and mostpreferably no more than 2% (especially less than 2%) is in aggregatedform. This stabilisation of non-aggregated protein is highlyadvantageous from the point of view of high effectiveness, low sideeffects and predictable absorption profile. Furthermore, it isincreasingly expected that protein/peptide therapeutics will have lowlevels of protein aggregation in order to secure regulatory approval.

The amount of bioactive agent to be formulated with the pre-formulationsof the present invention will depend upon the functional dose and theperiod during which the depot composition formed upon administration isto provide sustained release.

Typically, the dose formulated for a particular agent will be around theequivalent of the normal daily dose multiplied by the number of days theformulation is to provide release. Evidently this amount will need to betailored to take into account any adverse effects of a large dose at thebeginning of treatment and so this will generally be the maximum doseused. The precise amount suitable in any case will readily be determinedby suitable experimentation.

In one embodiment, the pre-formulations of the present invention willgenerally be administered parenterally. This administration willgenerally not be an intra-vascular method but will preferably besubcutaneous intracavitary or intramuscular.

Typically the administration will be by injection, which term is usedherein to indicate any method in which the formulation is passed throughthe skin, such as by needle, catheter or needle-less injector.

In parenteral (especially sub cutaneous) depot precursors, preferredactive agents are those suitable for systemic administration includingantibacterials (including amicacin, monocycline anddoxycycline), localand systemic anagesics (including bupivacain, tramadol, fentanyl,morphine, hydromorphone, methadone, oxycodone, codeine, asperine,acetaminophen), NSAIDS (such as ibuprofene, naproxene, keteprofene,indomethansine, sulindac, tolmethin, salysylic acids such assalisylamide, diflunisal), Cox1 or Cox2 inhibitors (such as celecoxib,rofecoxib, valdecoxib) anticancer agents (including octreotide,lanreotide, buserelin, luprorelin, goserelin, triptorelin, avorelin,deslorein, abarelix, degarelix, fulvestrant, interferon alpha,interferon beta, darbepoetin alpha, epoetin alpha, beta, delta, andpaclitaxel), antipsychotics (like bromperidol, risperidone, olanzapine,iloperidone, paliperadone, pipotiazine and zuclopenthixol), antivirals,anticonvulsants (for instance tiagabine topiramate or gabapentin) ornicotine, hormones (such as testosterone, and testosterone undecanoate,medroxyprogesterone, estradiol) growth hormones (like human growthhormone), and growth factors (like granulocyte macrophagecolony-stimulating factor)

In an alternative embodiment, the formulations of the present inventionmay form non-parenteral depots where the active agent is slowly releasedat a body surface. It is especially important in this embodiment thatthe pre-formulations of the invention and/or the liquid crystallinedepot compositions formed therefrom should preferably be bioadhesive.That is to say that the compositions should coat the surface to whichthey are applied and/or upon which they form as appropriate and shouldremain even when this surface is subject to a flow of air or liquidand/or rubbing. It is particularly preferable that the liquidcrystalline depot compositions formed should be stable to rinsing withwater. For example, a small volume of depot precursor may be applied toa body surface and be exposed to a flow of five hundred times its ownvolume of water per minute for 5 minutes. After this treatment, thecomposition can be considered bioadhesive if less than 50% of thebioactive agent has been lost. Preferably this level of loss will bematched when water equalling 1000 times and more preferably 10 000 timesthe volume of the composition is flowed past per minute for five, orpreferably 10, minutes.

Although the non-parenteral depot compositions of the present inventionmay absorb some or all of the water needed to form a liquid crystallinephase structure from the biological surfaces with which they arecontacted, some additional water may also be absorbed from thesurrounding air. In particular, where a thin layer of high surface areais formed then the affinity of the composition for water may besufficient for it to form a liquid crystalline phase structure bycontact with the water in the air. The “aqueous fluid” are referred toherein is thus, at least partially, air containing some moisture in thisembodiment.

Non-parenteral depot compositions will typically be generated byapplying the pre-formulation topically to a body surface or to a naturalor artificially generated body cavity and/or to the surface of animplant. This application may be by direct application of liquid such asby spraying, dipping, rinsing, application from a pad or ball roller,intra-cavity injection (e.g to an open cavity with or without the use ofa needle), painting, dropping (especially into the eyes) and similarmethods. A highly effective method is aerosol or pump spraying andevidently this requires that the viscosity of the pre-formulation be aslow as possible and is thus highly suited to the compositions of theinvention. Non-parenteral depots may, however, be used to administersystemic agents e.g. transmucosally or transdermally.

Non-parenteral depots may also be used for application to surfaces,particularly of implants and materials which will be in contact with thebody or a body part or fluid. Devices such as implants, catheters etc.may thus be treated e.g. by dipping or spraying with the preformulationsof the invention, which will form a robust layer to reduce theintroduction of infection. Anti-infective actives are particularlysuited to this aspect.

Conditions particularly suitable for causative or symptomatic treatmentby topical bioadhesive depot compositions of the present inventioninclude skin conditions (such as soreness resulting from any causeincluding chapping, scratching and skin conditions including eczema andherpes) eye conditions, genital soreness (including that due to genitalinfection such as genital herpes), infections and conditions for thefinger and/or toe nails (such as bacterial or fungal infections of thenails such as onychomycosis or poronychia). Topical-type bioadhesiveformulations may also be used to administer systemic active agents (e.g.medication), particularly by skin adsorption, oral, transdermal orrectal routes. Travel sickness medication is a preferred example, as isnicotine (e.g. in anti-smoking aids). Where context permits, “topicalapplication” as referred to herein includes systemic agents appliednon-parenterally to a specific region of the body.

Periodontal infections are particularly suitable for treatment by thecompositions of the present invention. In particular, known compositionsfor treating periodontal infection are difficult to apply or aregenerally ineffective. The most widely used periodontal depotcomposition comprises insertion of a collagen “chip” into theperiodontal space, from which an anti-infective agent is released. Thischip is difficult to insert and does not form to match the shape andvolume of the periodontal space, so that pockets of infection may remainuntreated. In contrast to this, the compositions of the presentinvention, applied as a low viscosity preformulation, can be easily andquickly injected into the periodontal space and will flow to conformexactly to that space and fill the available volume. The compositionsthen quickly absorb water to form a robust gel which is resistant toaqueous conditions of the mouth. The only known previous attempt at suchan injectible periodontal treatment relied on dispersions of relativelyhigh viscosity which were difficult to apply and were subject toundesirable phase separation. All of these drawbacks are now addressedin the compositions of the present invention as described herein. Highlysuitable actives for periodontal administration are antiinfectives,especially benzydamine, tramadol and chlorhexidine.

Non-parenteral depot compositions are also of significant benefit incombination with non-pharmaceutical active agents, such as cosmeticactives, fragrances, essential oils etc. Such non-pharmaceutical depotswill maintain the important aspects of bioadhesion and sustained releaseto provide prolonged cosmetic effects, but may easily be applied byspraying or wiping. This additionally applies to agents which have bothcosmetic and medical (especially prophylactic) benefits such assun-protective agents. Since the topical depot compositions providerobust, water resistant barriers which can solubilise high levels ofactives, they are especially suitable for sunscreens and sunblocks incombination with ultra violet light (UV, e.g. UVa, UVb and/or UVc)absorbing and/or scattering agents, particularly where high levels ofprotection is desirable. The compositions are furthermore highlybiocompatible and may act to moisten and soothe the skin during sunexposure.

Compositions of the invention containing soothing agents such as aloevera are also highly suitable for soothing and moistening applicationafter exposure to sunlight, or to skin which is dry, inflamed or damageddue to, for example irritation, burning or abrasion.

Active agents particularly suited to non-parenteral (e.g. topical) depotadministration, which comprises intra oral, buccal, nasal, ophthalmic,dermal, vaginal delivery routes, include antibacterials such aschlorhexidine, chloramphenicol, triclosan, tetracycline, terbinafine,tobramycin, fusidate sodium, butenafine, metronidazole (the latterparticularly for the (e.g. symtomatic) treatment of acne rosacea—adultacne or some vaginal infections), antiviral, including acyclovir, antiinfectives such as bibrocathol, ciprofloxacin, levofloxacin, localanalgesics such as benzydamine, lidocaine, prilocaine, xylocaine,bupivacaine, analgesics such as tramadol, fentanyl, morphine,hydromorphone, methadone, oxycodone, codeine, asperine, acetaminophen,NSAIDS such as ibuprofen, flurbiprofen, naproxene, ketoprofen,fenoprofen, diclofenac, etodalac, diflunisal, oxaproxin, piroxicam,piroxicam, indomethansine, sulindac, tolmethin, salysylic acids such assalisylamide and diflunisal, Cox1 or Cox2 inhibitors such as celecoxib,rofecoxib or valdecoxib, corticosteroids, anticancer and immunostimulating agents (for instance, metylaminolevulinat hydrocloride,interferon alpha and beta), anticonvulsants (for instance tiagabinetopiramate or gabapentin), hormones (such as testosterone, andtestosterone undecanoate, medroxyprogesterone, estradiol) growthhormones (like human growth hormone), and growth factors (likegranulocyte macrophage colony-stimulating factor), immuno suppressants(cyclosporine, sirolimus, tacrolimus), nicotine and antivirals (e.g.acyclovir).

Some specific actives found by the inventors to form highly effectivedepots of the present invention include the following:

For long acting injectable depot products of hydrophilic active agents;

-   i. octreotide (or other somatostatin analogues such as lanreotide    for treatment of carcoid and VIP producing tumours and acromegali).    Subcutaneous depots formable, especially with GDO and PC having a    sustained release duration of more than one month and showing less    than 20% octreotide degraded in one month in water-swollen depot at    37° C. Surprisingly good stability was observed and found to be    better than octreotide formulated in microspheres. Depot showed less    than 5% degradation in product preformulation over eight weeks at 4°    C.-   ii. human growth hormone. For treatment of growth disorders and    growth hormone deficiencies. Subcutaneous depot formable, especially    with GDO and PC having a sustained release duration of more than two    weeks-   iii. interferon alpha, for treatment of cancer and viral infections.    Subcutaneous depots formable, especially with GDO and PC, having a    sustained release duration of more than one month-   iv. leuprolide. Depots formable having continuous delivery    (preferably continuous delivery inside therapeutic window) for    minimum of one month.

For long acting injectable depots of lipophilic/amphiphilic actives;

-   i. risperidone-   ii. olanzapine-   iii. testosterone undecanoate

Depots i to iii formable having continuous delivery (preferablycontinuous delivery inside therapeutic window) for minimum of two weeks.

For topical bioadhesive, controlled release products for intraoral(including buccal & periodontal) administration;

-   i. benzydamine (local analgesic, anti inflammatory,) or other local    analgesic, analgesic, anti inflammatory, anti bacterial, anti fungal    or combination thereof. Composition provides sustained effect at    intraoral mucosa, in particular damaged, sensitised, infected mucosa    e.g. in patients suffering from oral mucositis (induced by e.g.    chemo- and radiotherapy). In particular for treatment of oral    mucositis.-   ii. tramadol (analgesic). Provides a composition with sustained    systemic analgesic effect.-   iii. chlorhexidine gluconate (antibacterial) for treatment of    periodontal and topical infections. Particularly for long acting    effect in periodontal pocket. Compositions result in depots    releasing chlorhexidine over more than 1 h, preferably more than 6    h, most preferably more than 24 h when applied as a liquid, forming    a bioadhesive gel in situ. Surface gel formation time observed to be    between 1 second. and 5 min.

Depots i to iii formable having high level of active agent incorporationand high degree of resistance to washing away. Preformulations in theform of a liquid administered as spray or liquid wash/rinse for i and iiand gel-forming liquid for iii, wherein liquid is applied to periodontalpocket, e.g. by injection.

For non-parenteral (e.g. topical or systemic) bioadhesive, controlledrelease products for nasal administration;

-   i. fentanyl (analgesic) provides rapid onset and sustained duration    analgesia when administered as spray-   ii. diazepam (anti anxiety) provides non-parenteral, nasal depot    with systemic effect giving rapid onset and sustained duration.    Administered as a spray

For topical bioadhesive, controlled release products for ophthalmicadministration;

-   i. diclofenac (NSAID) with sustained duration. Administered as in    situ phase forming liquid-   ii. pilocarpine (parasymptomimetic, cholinergic agonist) for    treatment of glaucoma.-   iii levocabastine hydrochloride, ketotifen fumarate providing liquid    for eye-dropping to give long lasting relief from allergic    conjunctivitis with long period between reapplication.-   iv Pilocarpine hydrochloride for the treatment of Sjögrens syndrome.-   v dexamethasone, (corticosteroid)-   vi chloramphenicol (primarily bacteriostatic antiinfective)-   vii indomethacin (NSAID)

Depots i to vii formulated as liquid spray or more preferably drops fordirect application to eye surface and provide in situ depot formationwith high resistance to washing out by tears and wear from blinking/eyerubbing.

Other actives suitable for ophthalmic compositions includeAntihistamines, Mast cell stabilizers, Nonsteroidal anti-inflammatorydrugs (NSAIDs), Corticosteroids (e.g. to treat allergic conjunctivitis),Anti-Glaucoma actives including inflow suppressing/inhibiting agents(beta blocking agents: timolol, betaxolol, carteolol, levobunolol, etc.,topical carbonic anhydrase inhibitors: dorzolamide, brinzolamide,sympathomimetics: epinephrine, dipivefrin, clonidine, apraclonidine,brimonidine), outflow facilitating agents (parasympathomimetics(cholinergic agonists): pilocarpine prostaglandin analogues and relatedcompounds: atanoprost, travoprost, bimatoprost, unoprostone)

For non-parenteral (e.g. topical or systemic) bioadhesive, controlledrelease products for dermatological administration;

-   i. acyclovir (antiviral). Composition generates a bioadhesive, film    forming product with sustained duration. Applied as spray or liquid-   ii. testosterone undecanoate (hormone deficiency). bioadhesive, film    forming composition with sustained duration. May be applied as    aerosol- or pump-spray, or as liquid.

Particularly suitable applications of dermatological formulations areanti-infective dermatological bioadhesive depots for protection inenvironments where contact with infective agents likely (e.g. human orveterinary surgery, abattoir work, certain types of cleaning etc.).Bioadhesive depots generated from composition of the invention providerobust and sustained protection for the wearer. The compositions withantiinfective agents may also be used in situations where skin sterilityof the wearer is important for the health of others, such as for nursesor doctors visiting multiple patients in hospital, where cross-infectionmust be avoided. A prior coating with a composition of the presentinvention may serve to provide resistance against picking up ofinfectives from one area and thus prevent transmission to another.

The pre-formulations of the present invention provide non-lamellarliquid crystalline depot compositions upon exposure to aqueous fluids,especially in vivo and in contact with body surfaces. As used herein,the term “non-lamellar” is used to indicate a normal or reversed liquidcrystalline phase (such as a cubic or hexagonal phase) or the L3 phaseor any combination thereof. The term liquid crystalline indicates allhexagonal, all cubic liquid crystalline phases and/or all mixturesthereof. Hexagonal as used herein indicates “normal” or “reversed”hexagonal (preferably reversed) and “cubic” indicates any cubic liquidcrystalline phase unless specified otherwise. By use of thepre-formulations of the present invention it is possible to generate anyphase structure present in the phase-diagram of components a and b withwater. This is because the pre-formulations can be generated with awider range of relative component concentrations than previous lipiddepot systems without risking phase separation or resulting in highlyviscous solutions for injection. In particular, the present inventionprovides for the use of phospholipid concentrations above 50% relativeto the total amphiphile content. This allows access to phases only seenat high phospholipid concentrations, particularly the hexagonal liquidcrystalline phases.

For many combinations of lipids, only certain non-lamellar phases exist,or exist in any stable state. It is a surprising feature of the presentinvention that compositions as described herein frequently exhibitnon-lamellar phases which are not present with many other combinationsof components. In one particularly advantageous embodiment, therefore,the present invention relates to compositions having a combination ofcomponents for which an I₂ and/or L₂ phase region exists when dilutedwith aqueous solvent. The presence or absence of such regions can betested easily for any particular combination by simple dilution of thecomposition with aqueous solvent and study of the resulting phasestructures by the methods described herein.

In a highly advantageous embodiment, the compositions of the inventionmay form an I₂ phase, or a mixed phase including I₂ phase upon contactwith water. The I₂ phase is a reversed cubic liquid crystalline phasehaving discontinuous aqueous regions. This phase is of particularadvantage in the controlled release of active agents and especially incombination with polar active agents, such as water soluble activesbecause the discontinuous polar domains prevent rapid diffusion of theactives. Depot precursors in the L₂ are highly effective in combinationwith an 12 phase depot formation. This is because the L₂ phase is aso-called “reversed micellar” phase having a continuous hydrophobicregion surrounding discrete polar cores. L₂ thus has similar advantageswith hydrophilic actives.

In transient stages after contact with body fluid the composition cancomprise multiple phases since the formation of an initial surface phasewill retard the passage of solvent into the core of the depot,especially with substantial sized administrations of internal depots.Without being bound by theory, it is believed that this transientformation of a surface phase, especially a liquid crystalline surfacephase, serves to dramatically reduce the “burst/lag” profile of thepresent compositions by immediately restricting the rate of exchangebetween the composition and the surroundings. Transient phases mayinclude (generally in order from the outside towards the centre of thedepot): H_(II) or L_(α), I₂, L₂, and liquid (solution). It is highlypreferred that the composition of the invention is capable forming atleast two and more preferably at least three of these phasessimultaneously at transient stages after contact with water atphysiological temperatures. In particular, it is highly preferred thatone of the phases formed, at least transiently, is the I₂ phase.

It is important to appreciate that the preformulations of the presentinvention are of low viscosity. As a result, these preformulations mustnot be in any bulk liquid crystalline phase since all liquid crystallinephases have a viscosity significantly higher than could be administeredby syringe or spray dispenser. The preformulations of the presentinvention will thus be in a non-liquid crystalline state, such as asolution, L₂ or L₃ phase, particularly solution or L₂. The L₂ phase asused herein throughout is preferably a “swollen” L₂ phase containinggreater than 10 wt % of solvent (component c) having a viscosityreducing effect. This is in contrast to a “concentrated” or “unswollen”L₂ phase containing no solvent, or a lesser amount of solvent, orcontaining a solvent (or mixture) which does not provide the decrease inviscosity associated with the oxygen-containing, low viscosity solventsspecified herein.

Upon administration, the pre-formulations of the present inventionundergo a phase structure transition from a low viscosity mixture to ahigh viscosity (generally tissue adherent) depot composition. Generallythis will be a transition from a molecular mixture, swollen L₂ and/or L₃phase to one or more (high viscosity) liquid crystalline phases such asnormal or reversed hexagonal or cubic liquid crystalline phases ormixtures thereof. As indicated above, further phase transitions may alsotake place following administration. Obviously, complete phasetransition is not necessary for the functioning of the invention but atleast a surface layer of the administered mixture will form a liquidcrystalline structure. Generally this transition will be rapid for atleast the surface region of the administered formulation (that part indirect contact with air, body surfaces and/or body fluids). This willmost preferably be over a few seconds or minutes (e.g. up to 30 minutes,preferably up to 10 minutes, more preferably 5 minutes of less). Theremainder of the composition may change phase to a liquid crystallinephase more slowly by diffusion and/or as the surface region disperses.

In one preferred embodiment, the present invention thus provides apre-formulation as described herein of which at least a portion forms ahexagonal liquid crystalline phase upon contact with an aqueous fluid.The thus-formed hexagonal phase may gradually disperse, releasing theactive agent, or may subsequently convert to a cubic liquid crystallinephase, which in turn then gradually disperses. It is believed that thehexagonal phase will provide a more rapid release of active agent, inparticular of hydrophilic active agent, than the cubic phase structure,especially the I₂ and L₂ phase. Thus, where the hexagonal phase formsprior to the cubic phase, this will result in an initial release ofactive agent to bring the concentration up to an effective levelrapidly, followed by the gradual release of a “maintenance dose” as thecubic phase degrades. In this way, the release profile may becontrolled.

Without being bound by theory, it is believed that upon exposure (e.g.to body fluids), the pre-formulations of the invention lose some or allof the organic solvent included therein (e.g. by diffusion and/orevaporation) and take in aqueous fluid from the bodily environment (e.g.moist air close to the body or the in vivo environment) such that atleast a part of the formulation generates a non-lamellar, particularlyliquid crystalline phase structure. In most cases these non-lamellarstructures are highly viscous and are not easily dissolved or dispersedinto the in vivo environment and are bioadhesive and thus not easilyrinsed or washed away. Furthermore, because the non-lamellar structurehas large polar, apolar and boundary regions, it is highly effective insolubilising and stabilising many types of active agents and protectingthese from degradation mechanisms. As the depot composition formed fromthe pre-formulation gradually degrades over a period of days, weeks ormonths, the active agent is gradually released and/or diffuses out fromthe composition. Since the environment within the depot composition isrelatively protected, the pre-formulations of the invention are highlysuitable for active agents with a relatively low biological half-life(see above).

It is an unexpected finding of the present inventors that thepre-formulations result in a depot composition that have very little“burst” effect in the active agent release profile. This is unexpectedbecause it might be expected that the low viscosity mixture (especiallyif this is a solution) of the pre-composition would rapidly lose activeagent upon exposure to water. In fact, pre-formulations of the inventionhave shown considerably less of an initial “burst” than previously knownpolymer-base depot compositions. This is illustrated in the Examplesbelow and Figures attached hereto. In one embodiment, the invention thusprovides injectable preformulations and resulting depot compositionswherein the highest plasma concentration of active after administrationis no more than 5 times the average concentration between 24 hours and 5days of administration. This ratio is preferably no more than 4 timesand most preferably no more than 3 times the average concentration.

In an additional aspect of the invention, the topical compositions maybe used to provide a physical barrier on body surfaces, in the absenceof any active agent. In particular, because of the very highbioadherance of the compositions, “barrier” coatings formed by sprayingor application of liquid may be formed from the present compositions soas to reduce contact with potential infective or irritant agents or toreduce soiling of the body surfaces. The robust nature of thecompositions and resistance to washing provide advantageouscharacteristics for such barriers, which could conveniently be appliedas a liquid or by spraying.

The Invention will now be further illustrated by reference to thefollowing non-limiting Examples and the attached Figures, in which;

FIG. 1 shows the cumulative release of methylene blue (MB) from a depotformulation comprising PC/GDO/EtOH (45/45/10 wt %) when injected intoexcess water;

FIG. 2 demonstrates the non-linear decrease of pre-formulation viscosityupon addition of N-methyl pyrolidinone (NMP) and EtOH;

FIG. 3 shows the plasma concentration (in rats) of salmon calcitonin(sCT) after subcutaneous injection of various PC/GDO/EtOH depotprecursors containing 500 μg sCT/g of formulation;

FIG. 4 shows the initial in vivo release (up to 48 hours) to plasma (inrats) of sCT from two different depot formulations followingsubcutaneous injection;

FIG. 5 shows the plasma concentration (in rats) of octreotide (OCT)following subcutaneous injection of a depot formulation comprisingPC/GDO/EtOH (36/54/10 wt %) containing 5 mg OCT/g formulation,corresponding to 0.5% drug load.

FIG. 6 shows the plasma concentration (in rats) of octreotide (OCT)following subcutaneous injection of a depot formulation comprisingPC/GDO/EtOH (47.5/47.5/5.0 wt %) containing 30 mg OCT/g formulation,corresponding to 3% drug load.

FIG. 7 displays the in vitro release in excess aqueous phase ofchlorhexidine from a depot formulation comprising PC/GDO/EtOH (36/54/10wt %) containing 50 mg chlorhexidine/g of formulation, corresponding to5% drug load.

EXAMPLES Example 1

Availability of Various Liquid Crystalline Phases in the Depot by Choiceof Composition

Injectable formulations containing different proportions of phosphatidylcholine (“PC”—Epikuron 200) and glycerol dioleate (GDO) and with EtOH assolvent were prepared to illustrate that various liquid crystallinephases can be accessed after equilibrating the depot precursorformulation with excess water.

Appropriate amounts of PC and EtOH were weighed in glass vials and themixture was placed on a shaker until the PC completely dissolved to forma clear liquid solution. GDO was then added to form an injectablehomogenous solution.

Each formulation was injected in a vial and equilibrated with excesswater. The phase behaviour was evaluated visually and between crossedpolarizes at 25° C. Results are presented in Table 1.

TABLE 1 PC GDO EtOH Phase in Formulation (wt %) (wt %) (wt %) H₂O A 22.567.5 10.0 L₂ B 28.8 61.2 10.0 I₂ C 45.0 45.0 10.0 H_(II) D 63.0 27.010.0 H_(II)/L_(α) L₂ = reversed micellar phase I₂ = reversed cubicliquid crystalline phase H_(II) = reversed hexagonal liquid crystallinephase L_(α) = lamellar phase

Example 2

In Vitro Release of a Water-Soluble Substance

A water-soluble colorant, methylene blue (MB) was dispersed informulation C (see Example 1) to a concentration of 11 mg/g formulation.When 0.5 g of the formulation was injected in 100 ml water a stiffreversed hexagonal Hit phase was formed. The absorbency of MB releasedto the aqueous phase was followed at 664 nm over a period of 10 days.The release study was performed in an Erlenmeyer flask at 37° C. andwith low magnetic stirring.

The release profile of MB (see FIG. 1) from the hexagonal phaseindicates that this (and similar) formulations are promising depotsystems. Furthermore, the formulation seems to give a low initial burst,and the release profile indicates that the substance can be released forseveral weeks; only about 50% of MB is released after 10 days.

Example 3

Viscosity in PC/GDO (6:4) or PC/GDO (3:7) on Addition of Solvent (EtOH,PG and NMP)

A mixture of PC/GDO/EtOH was manufactured according to the method inExample 1. All, or nearly all, of the EtOH was removed from the mixturewith a rotary evaporator (vacuum, 40° C., 1 h) and the resulting solidmixture were weighed in glass vial after which 2, 5, 10 or 20% of asolvent (EtOH, propylene glycol (PG) or n-methyl pyrrolidone (NMP)) wasadded. The samples were allowed to equilibrate several days before theviscosity was measured at a shear rate of 0.1 s⁻¹ with a Physica UDS 200rheometer at 25° C.

This example clearly illustrates the need for solvent with certain depotprecursors in order to obtain an injectable formulation (see FIG. 2).The viscosity of solvent-free PC/GDO mixtures increases with increasingratio of PC. Systems with low PC/GDO ratio (more GDO) are injectablewith a lower concentration of solvent.

Example 4

Composition and In Vitro Phase Study

The formulations were manufactured according to the method described inExample 1 with compositions according to Table 2. An active substance(peptide), salmon calcitonin (sCT), was added to each formulation to aconcentration of 500 μg sCT/g formulation. The formulations weredesigned as homogenous suspensions for parenteral administration (mixingrequired shortly prior to use since the drug is not completely dissolvedin the PC/GDO/EtOH system).

The phase study in this example is performed in excess of rat serum at37° C. in order to simulate an in vivo situation. Table 2 shows that thesame phases as those in water are formed (compare Table 1).

TABLE 2 PC GDO OA EtOH Phase in Formulation (wt %) (wt %) (wt %) (wt %)rat serum E 18 72 — 10 L₂ F 36 54 — 10 I₂ G 34 51 5 10 I₂ H 54 36 — 10H_(II) I 72 18 — 10 H_(II)/L_(α) OA = Oleic Acid

Example 5

Sterile Filtration of Formulations with Reduced Viscosity

To lower the viscosity with various solvents is sometimes necessary inorder to obtain an injectable formulation and to be able to administratethe system with a regular syringe (see Example 3). Another importanteffect from the viscosity-lowering solvent is that the formulations canbe sterile filtrated.

Formulations E to I in Example 4 were studied in a sterile filtrationtest by using a 0.22 μm filter (before addition of the activesubstance). Formulations E to H were successfully filtrated, butformulation I failed since the viscosity was too high. An asepticmanufacturing procedure was therefore needed for this formulation.

Example 6

In Vivo Release Study from Depot Formulations SubcutaneouslyAdministered

Formulations E to I in Example 4 were used in an in vivo drug releasestudy in rat. The formulations were administrated subcutaneously betweenthe scapulae by using a syringe (21G, 0.6 mm×30 mm) and the dose of sCTwas 500 μg/kg body weight. The release profile was monitored for aperiod of 13 days. The sCT concentration in the rat plasma samples wasanalysed with sandwich-type immunoassay using a commercial kit fromDSLabs.

FIG. 3 shows the results (n=4). A pure triglyceride vehicle based onsesame oil was selected as a lipid reference system.

Example 7

In Vivo Release Study in the Initial Phase

Formulations F and G as in Example 6 were used in an in vivo study inrat designed to investigate the initial “burst effect”. From FIG. 4(n=8) it appears that none of the investigated formulations has a severeburst effect.

Example 8: Preparation of Depot Precursor Compositions with VariousSolvents

Depending on composition of the formulation and the nature andconcentration of active substance certain solvents may be preferable.

Depot precursor formulations (PC/GDO/solvent (36/54/10)) were preparedby with various solvents; NMP, PG, PEG400, glycerol/EtOH (90/10) by themethod of Example 1. All depot precursor compositions were homogeneousone phase solutions with a viscosity that enabled injection through asyringe (23G—i.e. 23 gauge needle; 0.6 mm×30 mm). After injectingformulation precursors into excess water a liquid crystalline phase inthe form of a high viscous monolith rapidly formed with NMP and PGcontaining precursors. The liquid crystalline phase had a reversed cubicmicellar (I₂) structure. With PEG400, glycerol/EtOH (90/10) theviscosification/solidification process was much slower and initially theliquid precursor transformed to a soft somewhat sticky piece. Thedifference in appearance probably reflects the slower dissolution ofPEG400 and glycerol towards the excess aqueous phase as compared to thatof EtOH, NMP and PG.

Example 9: Preparation of Depot Composition Containing Human GrowthHormone (HGH)

Human growth hormone (hGH) plays a critical role in stimulating bodygrowth and development, and is involved in the production of muscleprotein and in the breakdown of fats. A deficiency of the hormoneadversely affects numerous body processes such as lipid profile, insulinstatus, physical performance, bone-mineral density and quality of life.A targeted dose every 2 weeks is estimated at 0.10 to 0.24 mg/kg of bodyweight.

1 ml of a 2 weeks depot formulation precursor was formed by sequentiallymixing 10 mg hGH and 360 mg PC in 0.1 ml NMP. 540 mg GDO was added tothe mixture to obtain a low viscosity depot formulation precursor.Injecting the formulation precursor into excess water (syringe 23G; 0.6mm×30 mm) resulted in a monolithic liquid crystalline phase (I₂structure).

Example 10: Preparation of Depot Composition Containing a SparinglySoluble Active Substance

Risperidone is an antipsychotic medication agent belonging to thechemical class of benzisoxazole derivatives. It is a very strongdopamine blocker (antagonist); ie, it inhibits functioning of dopaminereceptors, it is practically insoluble in water, and it has log(P)=3.49.

1 g of a depot formulation containing 50 mg of risperidone was preparedby dissolving the active substance in 0.7 g of a mixture 95% wt in EtOH(99.5%) and 5% wt in acetic acid. 0.34 g PC and 0.51 g GDO weresubsequently dissolved in this solution followed by solvent reduction toremaining 0.15 g solvent (0.55 g was evaporated under vacuum). Thecomposition of the final homogenous and clear depot formulation with 50mg risperidone was PC/GDO/solvent/risperidone (32/49/14/5). Injectingthe formulation precursor into excess water (syringe 23G; 0.6 mm×30 mm)resulted in a monolithic liquid crystalline phase (12 structure). I.e.the amount of active substance (5%) did not change monolith formationand phase behavior after exposure to an aqueous environment.

Example 11: Alternate Preparation of Depot Composition ContainingRisperidone

A risperidone depot precursor formulation could also be prepared byusing a solvent mixture composed of 90% wt EtOH (99.5%) and 10% wt inacetic acid.

50 mg of risperidone was dissolved in 0.7 g of the solvent mixture,after which 0.36 g PC and 0.54 g GDO were subsequently dissolved in thissolution. 0.60 g of the solvent mixture was evaporated under vacuum to ahomogenous and clear depot formulation precursor with 50 mg risperidone(PC/GDO/solvent/risperidone (34/51/10/5)). Injecting the formulationprecursor into excess water (syringe 23G; 0.6 mm×30 mm) resulted in amonolithic liquid crystalline phase (12 structure). I.e. the amount ofactive substance (5%) did not change monolith formation and phasebehavior after exposure to an aqueous environment.

Example 12: Temperature Stability of Depot Composition Containing aSparingly Soluble Active Substance

The risperdone depot precursor formulations in examples 10 and 11 weretested for stability against crystallization during storage. Eachformulation was stable at 25° C. for at least two weeks and at +8° C.for at least one week.

Example 13: Preparation of Depot Composition Containing Benzydamine

Benzydamine is a non-steroidal antiinflammatory drug and is extensivelyused as a topical drug in inflammatory conditions.

1 g of a depot formulation containing 1.5 mg benzydamine was prepared bydissolving the active substance in a mixture of PC/GDO/EtOH (36/54/10)prepared as described in Example 1. The depot composition was stableagainst crystallization during storage at 25° C. for at least two weeks.Equilibration of the formulation precursor with excess water resulted ina high viscous monolithic liquid crystalline phase (I₂ structure).

Example 14: Robustness of the Behaviour of the Formulation AgainstVariations in the Excipient Quality

Depot precursor formulations were prepared with several different GDOqualities (supplied by Danisco, Dk), Table 3, using the method ofExample 1. The final depot precursors contained 36% wt PC, 54% wt GDO,and 10% wt EtOH. The appearance of the depot precursors was insensitiveto variation in the quality used, and after contact with excess water amonolith was formed with a reversed micellar cubic phase behaviour (I₂structure).

TABLE 3 Tested qualities of GDO. GDO Monoglyceride DiglycerideTriglyceride quality (% wt) (% wt) (% wt) A 10.9 87.5 1.6 B 4.8 93.6 1.6C 1.0 97.3 1.7 D 10.1 80.8 10.1 E 2.9 88.9 8.2 F 0.9 89.0 10.1

Example 15: Preparation of Depot Composition Containing Saturated PC(Epikuron 200SH)

Depot precursor formulations were prepared with various amounts PCcomprising saturated hydrocarbon chains by addition of Epikuron 200SHdirectly to a mixture of PC/GDO/EtOH, prepared as for Example 1. Theformulations are shown in Table 4. All precursor formulations werehomogenous one phase samples in RT, while they became more viscous withincreasing amount Epikuron 200SH. Injecting the depot precursor intoexcess water gave a monolith comprising a reversed miceller cubic (I₂)structure. Monoliths formed from samples containing higher amounts ofEpikuron 200SH became turbid, possibly indicating segregation betweenEpikuron 200SH and the other components upon exposure to water andformation of the I2 phase.

TABLE 4 Depot composition containing saturated PC Saturated PC, Epikuron200SH PC GDO EtOH Formulation (% wt) (% wt) (% wt) (% wt) G1 3.9 34.651.9 9.6 G2 7.0 33.5 50.2 9.3 G3 14.3 30.8 46.3 8.6

Example 16: Preparation of Depot Precursor being a Dispersion orSolution of the Peptide Salmon Calcitonin

By adding 500 μg sCT/g formulation to a solution of PC/GDO/EtOH(36/54/10), obtained as in Example 1, a dispersion of sCT was formed.

In an alternative method, 500 μg sCT was dissolved in excess of EtOHfollowed by addition of PC and GDO. The solvent concentration was thenreduced (EtOH evaporation) to form a homogenous (active drug insolution) formulation. This latter technique can be used to obtainhigher drug loads. Precursor compositions corresponding to at least 1500μg dissolved sCT per gram of the final depot precursor composition couldbe obtained by this method.

Example 17: In Vivo Release Study from Depot Formulation SubcutaneouslyAdministered

The two sCT compositions described in Example 16 were administered in anin vivo rat model by subcutaneous injection (between the scapulae). Thefirst depot precursor having dispersed sCT was found to give somewhatunstable initial plasma concentrations, while the second depotprecursor, having sCT dissolved therein, gave much more stable initialplasma levels (see Table 5).

TABLE 5 Coefficient of Formulations variation (% CV) Dispersed: 500 μgsCT/g 32-127 PC/GDO/EtOH (36/54/10) Dissolved: 500 μg sCT/g 20-37 PC/GDO/EtOH (36/54/10)

Example 18: Preparation of Depot Composition Containing the PeptideOctreotide

Octreotide is an acetate salt of a synthetic octa-peptide and is similarto the hormone somatostatin. Octreotide decreases production ofsubstances such as growth hormone, insulin and glucagons. It is used intreatment of acromegaly, and to reduce flushing and watery diarrhoeacaused by metastatic cancerous tumors (carcinoid syndrome) or tumorscalled vasoactive intestinal peptide tumors (VIPomas).

24 mg or 60 mg octreotide was dissolved in 0.1 g EtOH. 0.36 g PC and0.54 g GDO were subsequently dissolved in this solution and a depotformulation precursor was obtained. Injecting the formulation precursorinto excess aqueous phase (syringe 23G; 0.6 mm×30 mm) resulted in amonolithic liquid crystalline phase (I₂ structure). I.e. octreotide(2.4% or 6.0%) did not change monolith formation and phase behaviourafter exposure to an aqueous environment.

The octreotide depot precursor formulations in this Example were testedfor stability against crystallization during storage. Each formulationwas stable at 4-8° C. for at least two weeks.

Example 19: In Vivo Release Study from Depot Formulation ContainingOctreotide Subcutaneously Administered

In an in vivo rat model the drug release of octreotide was followedduring 28 days. The formulations were administered subcutaneouslybetween the scapulae by using a syringe (23G, 0.6 mm×25 mm). Theoctreotide concentration in the rat plasma was followed for a period of28 days (see FIG. 5). The dose was 5 mg/kg and volume 1 ml/kgcorresponding to a drug load of 0.5% octreotide in the depot formulationprecursor (PC/GDO/EtOH (36/54/10)).

From FIG. 5 (n=3) it appears that the investigated formulation gives arelease profile essentially without a burst effect.

FIG. 5 shows Octreotide plasma levels in the rat model followingadministration of octreotide formulation precursor (0.5% in octreotide).

Example 20: Degradation of Depot Formulation in the Rat

Various volumes (1, 2, 6 ml/kg) of the depot precursor (36% wt PC, 54%wt GDO, and 10% wt EtOH) were injected in the rat and were removed againafter a period of 14 days. It was found that substantial amounts of theformulations were still present subcutaneously in the rat after thistime, see Table 6.

TABLE 6 Mean diameter of depot monolith. Mean diameter Mean diameterDose (ml/kg) day 3 (mm) day 14 (mm) 1 (n = 3) 15.8 12.5 2 (n = 3) 18.515.3 6 (n = 3) 23.3 19.3

Example 21: In Vitro Study of Formation of Depot Monolith afterInjection of Depot Formulation Precursor Between the Bone and Periostium

A precursor (36% wt PC, 54% wt GDO, and 10% wt EtOH prepared asdescribed in Example 1) was injected by syringe between the bone andperiostium. The composition was observed to spread to fill voids andafter uptake of aqueous fluids formed a monolith that was bioadhesive toboth the bone and periostium.

Example 22: Bioadhesive Spray of Depot Precursor Formulation

A pump spray bottle was found to be a convenient way to apply theformulation topically, e.g. to the skin or the oral mucosa.

A depot precursor formulation prepared as in Example 1 (36% wt PC, 54%wt GDO, and 10% wt EtOH) was sprayed with a pump spray bottle onto theskin and oral mucosa. A film with solid mechanical properties formedshortly after application.

Example 23: Robustness of a Topical Film

After applying the depot precursor formulation, as described in Example22, (36% wt PC, 54% wt GDO, and 10% wt EtOH) to the skin, the appliedformulation was exposed to flushing water (10 L/min) for 10 minutes. Theformulation showed excellent bioadhesive properties and resistanceagainst rinsing and no loss of the formulation could be discerned.

Example 24: Formation of Cubic Phase with Solid Properties afterExposure of Depot Precursor Formulation to Air

After exposing a depot precursor formulation prepared as described inExample 1 (36% wt PC, 54% wt GDO, and 10% wt EtOH) to air (RT, relativehumidity 40%) for at least 3 hours, a solid cubic phase was formed. Thisformation of a cubic phase structure demonstrates that a topical filmwill acquire bulk non-lamellar depot properties after applicationwithout the need for direct exposure to excess aqueous fluid.

Example 25: Formulation to Treat Periodontitis or Perimplantitis

In order to treat periodontitis or perimplantitis an antibacterialformulation is injected in the periodontal pocket, and a prolongedeffect of the formulation is normally desired.

100 μL of a formulation as prepared in Example 1, with the addition ofthe antibiotic chlorohexidine (PC/GDO/EtOH/chlorhexidine (35/53/10/2)),is injected via a syringe into a rat peridontal pocket. The injectedcomposition is observed to transform from the low viscous formulation,and which initially spreads out to fill voids, to form a solid mass byuptake of gingival fluids. An antibacterial depot system is thusprovided.

Chlorhexidine remains at clinically effective levels (MIC 125 μg/ml) inthe GCF of the periodontal pockets for over 1 week. The depot system iscompletely degraded by enzymes within 7 to 10 days and does not need tobe removed.

Example 26: Alternate Antibacterial Formulation to Treat Periodontitisor Perimplantitis

An alternate antibacterial formulation was provided by a formulationprepared as described in Example 1 and containing the antibacterialdetergent Gardol (Glycine, N-methyl-N-(1-oxododecyl)-, sodium salt)(PC/GDO/EtOH/Gardol (34/51/10/5)). This formulation is injected into therat periodontal pocket.

Gardol is observed to remain at clinically effective levels in the GCFof the periodontal pockets for a prolonged period (several days). Thedepot system is completely degraded by enzymes within 7 to 10 days anddid not need to be removed.

Example 27: Adhesion of the Formulation to High Energy Surfaces

In order to treat perimplantitis, adhesion not only to biologicalsurfaces but also to high energy surfaces such as a gold or titaniumimplant is important. It is also important that the formulation adheresto ceramic and plastic surfaces.

A formulation (PC/GDO/EtOH (36/54/10)) as prepared in Example 1 wasapplied to various surfaces in the oral cavity. The composition showedexcellent adhesion to ceramic, plastic, gold, as well as to a normaltooth surface and could not be rinsed away by excess aqueous fluid. Thedepot resulting from the composition stayed at the site in the oralcavity where it was applied for at least 6 h.

Example 28: Bioadhesive Sustained Release Formulation of Sodium Fluoridefor Use on the Teeth

Fluoride containing compounds are often needed to oppose caries attackand a bioadhesive formulation precursor with depot effect was preparedas indicated in Example 1 from a mixture of PC/GDO/EtOH/sodium fluoride(35/53/10/2). The formulation was a dispersion of sodium fluoride sinceit could not be dissolved in the precursor. The liquid formulation wasapplied to the teeth with the aid of a brush. By uptake of saliva theformulation solidified and formed a depot providing sustained release ofsodium fluoride for an extended period (several hours).

Example 29: Oral Cavity Spray Depot Composition

To be suitable as a topical depot system in the oral cavity themechanical properties of the system was adjusted by decreasing thePC/GDO ratio.

A mixture containing PC/GDO/EtOH (27/63/10) was prepared according toExample 1. A drop of patent blue was added to visualize the formulationafter application. About 300 μl of the formulation was sprayed into theoral cavity with pump spray bottle. Shortly after application theformulation viscosified/solidified since it underwent a phasetransformation by uptake of aqueous fluid (saliva) and loss of solvent(EtOH). The formulation had excellent bioadhesion to keritinizedsurfaces such as the hard palate and the gum. Here the film lasted forseveral hours despite saliva secretion and mechanical wear by thetongue. At soft mucosal surfaces the duration was much shorter(minutes).

Example 30: Oral Cavity Liquid Depot Composition

To be suitable for application with a pipette to the oral cavity thesolidification/viscosification of the formulation has to be delayedrelative to the spray formulation.

This is to allow the formulation to be conveniently distributed with thetongue to a thin film in the oral cavity after application.

Propylene glycol (PG) and EtOH were added to a formulation prepared asin Example 1, to the final composition PC/GDO/EtOH/PG (24/56/10/10). 300μl of the formulation was conveniently applied with a pipette to theoral cavity and distributed with the tongue to a thin film in the oralcavity. After about 20 seconds the viscosification of the formulationstarted since it underwent a phase transformation by uptake of aqueousfluid (saliva) and loss of solvent (EtOH and PG). After about one minutethe solidification/viscosification appeared to be finished. Theformulation had excellent bioadhesion to keritinized surfaces such asthe hard palate and the gum. Here the film lasted for several hoursdespite saliva secretion and mechanical wear by the tongue. At softmucosal surfaces the duration was much shorter (minutes).

Example 31—Bioadhesive Depot for Nails

The mixture in Example 29 was sprayed to the nail bed and in between thetoes. The formulation solidifies/viscosifies slowly by uptake of aqueousfluids (cf. sweat). The solidification can be speeded up by adding waterafter spray application. The formulation had excellent bioadhesiveproperties and had a duration for several hours.

Example 32: Loading Capacity of the Bioactive Agent Benzydamine in theFormulation Precursors

Formulations with compositions as specified in Table 7 were preparedusing the method in Example 1. An excess amount of benzydamine (50 mg)was added to 0.5 g of the formulations. The vials were placed on ashaker at 15° C. for three days after which the solutions were filteredthrough a filter (0.45 μm) to get rid of crystals of undissolvedbenzydamine. The benzydamine concentration in each formulation wasdetermined with reversed phase gradient HPLC and UV detection at 306 nmand the results are given in Table 7.

TABLE 7 Benzydamine Composition GDO/ concentration PC(Lipoid S100)/EtOHin formulation 67.5/22.5/10 3.4% 63/27/10 3.2% 58.5/31.5/10 3.3%60/20/20 4.0% 56/24/20 4.5% 52/28/20 4.3%

Example 33: Compositions Containing PC and Tocopherol

Depot precursor formulations were prepared with several differentPC/a-tocopherol compositions using the method of Example 1 (PC was firstdissolved in the appropriate amount of EtOH and thereafter a-tocopherolwas added to give clear homogenous solutions).

Each formulation was injected in a vial and equilibrated with excesswater. The phase behaviour was evaluated visually and between crossedpolarizes at 25° C. Results are presented in Table 8.

TABLE 8 α- Phase in tocopherol PC Ethanol excess H₂O 2.25 g 2.25 g 0.5 gH_(II) 2.7 g 1.8 g 0.5 g H_(II)/I₂ 3.15 g 1.35 g 0.5 g I₂ 3.6 g 0.9 g0.5 g I₂/L₂

Example 34: Composition Containing Octreotide

60 mg octreotide was dissolved in 0.1 g EtOH. 0.25 g PC and 0.59 ga-tocopherol were subsequently dissolved in this solution and a depotformulation precursor was obtained. Injecting the formulation precursorinto excess aqueous solution (phosphate buffered saline—PBS) resulted ina monolithic liquid crystalline phase (I₂ structure) i.e. octreotide(6.0%) did not change monolith formation and phase behaviour afterexposure to an aqueous environment.

The octreotide depot precursor formulation in this Example was testedfor stability against crystallization during storage. The formulationwas stable at 4-8° C. for at least two weeks.

Example 35: In Vitro Release of Water-Soluble Disodium Fluorescein

A water-soluble colorant, disodium fluorescein (Fluo), was dissolved ina formulation containing PC/α-tocopherol/Ethanol (27/63/10 wt %) to aconcentration of 5 mg Fluo/g formulation. When 0.1 g of the formulationwas injected in 2 ml of phosphate buffered saline (PBS) a reversedmicellar (I₂) phase was formed. The absorbency of Fluo released to theaqueous phase was followed at 490 nm over a period of 3 days. Therelease study was performed in a 3 mL vial capped with an aluminiumfully tear off cap at 37° C. The vial was placed on a shaking table at150 rpm.

The release of Fluo from the PC/α-tocopherol formulation (see Table 9)indicates that this (and similar) formulations are promising depotsystems. Furthermore, the absence of a burst effect is noteworthy, andthe release indicates that the substance can be released for severalweeks to months; only about 0.4% of Fluo is released after 3 days.

TABLE 9 % release (37° C.) Formulation 24 h 72 hPC/α-tocopherol/EtOH:27/63/10 wt % <0.1* 0.43 *Release below detectionlimit of the absorbance assay

Example 36: Formulations of the Analgesic/Antiinflammatory Benzydamine

Formulations were prepared as in Example 1 by mixing benzydamine with amixture of GDO, PC, ethanol and optionally PG/AP in the followingproportions.

Formulation BZD GDO PC EtOH PG AP 1 3.0 53.3 28.7 10.0 5.0 0.01 2 3.053.3 28.7 15.0 0 0.01 3 3.0 57.4 24.6 10.0 5.0 0.01 4 3.0 49.2 32.8 10.05.0 0.01 where BZD is benzydamine, EtOH is ethanol, PC is LIPOID S100soybean phosphatidylcholine, GDO is glycerol dioleate, PG is propyleneglycol, and AP is ascorbyl palmitate.

All formulations are low viscosity liquids which generate liquidcrystalline phase compositions upon exposure to aqueous conditions.

Example 37: Fentanyl Nasal Formulation

Formulations were prepared as in Example 1 by mixing the narcoticanalgesic fentanyl with a mixture of GDO, PC, ethanol and optionally PGin the following proportions.

Formulation Fentanyl PC GDO EtOH PG 1 0.05 34 51 10 5 2 0.05 36 54 10 —3 0.05 42 43 10 5 4 0.05 45 45 10 — 5 0.15 34 51 10 5 6 0.15 36 54 10 —7 0.05 30 45 15 10  8 0.15 30 45 15 10  where EtOH is ethanol, PC isLIPOID S100 soybean phosphatidylcholine, GDO is glycerol dioleate, andPG is propylene glycol

All formulations are low viscosity liquids suitable for administrationby nasal spray, which generate liquid crystalline phase compositionsupon exposure to aqueous conditions.

Example 38: Diazepam Nasal Formulation

Formulations were prepared as in previous examples by mixing thebenzodiazepine antianxiety agent diazepam with a mixture of GDO, PC,ethanol and optionally PG in the following proportions.

Formulation Diazepam PC GDO EtOH PG 1 5 32 48 10 5 2 5 34 51 10 — 3 1037 38 10 5 4 10 40 40 10 — 5 10 30 45 10 5 6 10 32 48 10 — 7 10 26 39 1510  8 10 30 45 15 — where EtOH is ethanol, PC is LIPOID S100 soybeanphosphatidylcholine, GDO is glycerol dioleate, and PG is propyleneglycol

All formulations are low viscosity liquids suitable for administrationby nasal spray, which generate liquid crystalline phase compositionsupon exposure to aqueous conditions.

Example 39: Interferon Alpha-2a

Interferons (IFNs) are used as a treatment for many types of systemiccancer, often in combination with chemotherapy or radiation. Recent datasuggest that IFN Alpha is a multifunctional immunomodulatory cytokinewith profound effects on the cytokine cascade including severalanti-inflammatory properties. These newly identified immunoregulatoryand anti-inflammatory functions may also be of importance in treatmentof diseases such as chronic viral hepatitis and help to explain some ofthe IFN mechanisms.

A non-aqueous precursor formulation was formed by dissolving PC (360 mg)and GDO (540 mg) in EtOH (100 mg). Interferon Alpha-2a (4 mg) wasdissolved in water (76 mg) and this solution was thereafter added to thenon-aqueous precursor formulation to form a depot formulation precursorof low viscosity.

Injecting the depot precursor into excess water (syringe 23 G; 0.6 mm×30mm) resulted in a monolithic liquid crystalline phase (I₂ structure).

Example 40 Leuprorelin (Leuprolide)

Leuprorelin acetate (or leuprolide acetate) is a synthetic nonapeptideanalogue of naturally occurring gonadotropin releasing hormone (GnRH orLH-RH) that, when given continuously (e.g. as a depot formulation),inhibits pituitary gonadotropin secretion and suppresses testicular andovarion steroidogenesis. Leuprorelin is used for the treatment ofadvanced prostate cancer.

A depot formulation precursor was formed by sequentially dissolving 22.5mg leuprorelin acetate and 360 mg PC in 100 mg of NMP. 540 mg of GDO wasadded to the mixture yielding a molecular solution depot formulationprecursor of low viscosity. Injecting the formulation precursor intoexcess water (syringe 23 G; 0.6 mm×30 mm) resulted in a monolithicliquid crystalline phase (12 structure).

Example 41: Alendronate

Bisphosphonates are structural analogues of pyrophosphates and havepharmacologic activity specific for bone due to the strong affinity ofbisphosphonates for hydroxyapatite, a major inorganic component of bone.The compounds are used to treat postmenopausal osteoporosis,hypercalcemia of malignancy and metastatic bone disease (MBD).

A non-aqueous precursor formulation was formed by dissolving PC (360 mg)and GDO (540 mg) in EtOH (100 mg). Alendronate (12 mg) was dissolved inwater (80 mg) and this solution was thereafter added to the non-aqueousprecursor formulation to form a depot formulation precursor of lowviscosity. Injecting the depot precursor into excess water (syringe 23G; 0.6 mm×30 mm) resulted in a monolithic liquid crystalline phase (I₂structure).

Example 42: Olanzapine

Olanzapine is a low molecular weight drug used for the treatment ofpatients with schizophrenia.

A depot formulation precursor was formed by sequentially mixing 50 mgolanzapine, 360 mg PC and 100 mg of EtOH. 540 mg of GDO was added to themixture resulting in the final depot formulation precursor.

Injecting the formulation precursor into excess water (syringe 23 G; 0.6mm×30 mm) resulted in a monolithic liquid crystalline phase (12structure).

Example 43: Acne Formulations with Clindamycin

Formulations were prepared as in previous examples by mixing thesemisynthetic antibiotic clindamycin (free base or salt) with a mixtureof GDO, PC, ethanol and PG in the following proportions (by weight).

Formulation PC GDO EtOH PG Clindamycin HCl 1 1 30 54 10 5 2 2 29 54 10 53 1 34 50 10 5 4 2 33 50 10 5 Clindamycin base 5 1 30 54 10 5 6 2 29 5410 5 7 1 33 54 2 10 8 2 32 54 2 10

The resulting preformulations are low viscosity liquids which, afterapplication resistant to water, sweat, etc. The formulation are appliedlocally on the skin as a gel or by spraying and are bioadhesive withgood film-forming properties.

Example 44: Further Examples of Viscosity in PC/GDO Mixtures on Additionof Co-Solvent

Mixtures of PC/GDO and co-solvent were prepared according to the methodsof Example 1 and Example 3 in the proportions indicated in the tablebelow. The samples were allowed to equilibrate for several days beforeviscosity measurements were performed using a Physica UDS 200 rheometerat 25° C.

PC/GDO EtOH/ Glycerol/ H₂O/ Viscosity/ Sample (wt/wt) wt % wt % wt %mPas 1 50/50 3 — — 1900 2 50/50 5 — — 780 3 50/50 7 — — 430 4 50/50 8 —— 300 5 50/50 10 — — 210 6 50/50 15 — — 100 7 45/55 3 — — 1350 8 45/55 5— — 540 9 45/55 7 — — 320 10 45/55 8 — — 250 11 45/55 10 — — 150 1245/55 15 — — 85 13 40/60 3 — — 740 14 40/60 5 — — 400 15 40/60 7 — — 24016 40/60 8 — — 200 17 40/60 10 — — 130 18 40/60 15 — — 57 19 40/60 — 10— 8*10⁶ 20 40/60 — — 3 2.5*10⁸   21 40/60 — — 5 4*10⁷

This example further illustrates the need for a solvent with viscositylowering properties in order to obtain injectable formulations. Themixtures containing glycerol (sample 19) or water (samples 20 and 21)are too viscous to be injectable at solvent concentrations equivalent tothe samples containing EtOH (compare with samples 13, 14 and 17).

Example 45: Occtreotide Formulation Compositions

Formulations were prepared as in Example 1 by mixing the peptide activeoctreotide with a mixture of GDO (at one of several purity levels) ortocopherol, PC, ethanol and optionally dioleoyl PG in the followingproportions (by weight)

For- mula- tion OCT EtOH PC GDO1 GDO2 GDO3 TP DOPG E 2 10 35.2 — — 52.8— — F 2 10 35.2 52.8 — — — — G 2 10 35.2 — 52.8 — — — H 2 10 26.4 — — —61.6 — I 1 10 35.6 53.4 — — — — J 2 5 37.2 — — 55.8 — — K 3 5 36.8 — —55.2 — — L 6 5 35.6 — — 53.5 — — M 3 5 35.8 — — 55.2 — 1 N 3 5 33.8 — —55.2 — 3 O 3 5 30.8 — — 55.2 — 6 P 3 5 46 — — 46 — — Q 3 10 43.5 — —43.5 — — R 6 10 42 — — 42 — — S 3 7 45 — — 45 — — T 6 7 43.5 — — 43.5 —— where OCT is octreotide, EtOH is ethanol, PC is LIPOID S100 soybeanphosphatidylcholine, GDO is glycerol dioleate, TP is α-tocopherol, DOPGis dioleoyl phosphatidylglycerol

GDO quality (according to AC) Monoglycerides Diglycerides TriglyceridesGDO1 10.9% 87.5% 1.4% GDO2 4.2% 92.1% 3.5% GDO3 0.5% 95.3% 4.0%

Formulation P (for composition see above) was administered bys.c.injection in the rat at a level of 1 ml formulation per kg bodyweight, corresponding to 30 mg/kg of octreotide.

Octreotide plasma levels after administration were monitored for 5 daysto examine any burst profile. It was observed that the highest plasmaconcentration was less than three fold greater than the average plasaconcentration over the first 5 days.

The results of the study are shown in FIG. 6

Example 46: Sunscreen Formulations

Formulations were prepared as in Example 1 by mixing each of several UVabsorbing/scattering agents with a mixture of GDO, PC, and ethanol inthe following proportions (by weight)

Tioveil Formu- Tioveil Spectraveil Solaveil 50 lation PC GDO EtOH CM FINCT-100 MOTG 1 38 42 5 — — — 15 2 38 42 5 — — 15 — 3 37 38 5 15 5 — —Where TIOVEIL CM (Uniqema) comprises Cyclomethicone (and) TitaniumDioxide (and) Dimethicone Copolyol (and) Aluminium Stearate (and)Alumina, SPECTRAVEIL FIN (Uniqema) comprises Zinc Oxide (and) C12-15Alkyl Benzoate (and) Polyhydroxystearic Acid, SOLAVEIL CT-100 (Uniqema)comprises C12-15 Alkyl Benzoate (and) Titanium Dioxide (and)Polyhydroxystearic Acid (and) Aluminum Stearate (and) Alumina, andTIOVEIL 50 MOTG (Uniqema) comprises Titanium Dioxide (and)Caprylic/Capric Triglyceride (and) Mineral Oil (and) PolyhydroxystearicAcid (and) Aluminum Stearate (and) Alumina.

The resulting formulation precursors show low viscosity upon formulationand are readily applied by pump spray. Upon contact with body surfaces aresilient UV protective layer is formed.

Example 47: Chlorhexidine Periodontal Depots

Formulations were prepared as in Example 1 by mixing the antiinfectiveagent chlorhexidine digluconate with a mixture of GDO, PC, and ethanolin the following proportions (by weight)

TABLE Chlorhexidine digluconate depot formulation compositions.Chlorhexidine Formulation digluconate PC GDO EtOH A 5 34 51 10 B 5 36 545 C 7 33 50 10 D 10 32 48 10 E 15 30 45 10

The chlorhexidine depot preformulations have low viscosity and areeasily administered to the periodontal pocket. The compositions providebetter distribution and spreading of the active substance throughout theperiodontal pocket when compared to current products, such asPeriochip®.

The depot formed after application gives protection against re-infectionof the pocket. The depot also has excellent bioadhesive properties andsticks to mucosal, teeth and bone surfaces.

Release of chlorhexidine digluconate from 250 mg Formulation A (seeabove) in 0.9% aqueous NaCl (500 ml) was studied. The formulation washeld in a cylindrical metal cup which was placed in a teflon holder atthe bottom of a standard USP release bath. The contact area between theformulation and surrounding saline solution was 2.4 cm², and thesolution was stirred by paddle at 100 rpm.

The release curve shown in FIG. 7 demonstrates the sustained andessentially uniform release of chlorhexidine from the formulation over aperiod of 24 hours.

1. A pre-formulation comprising a low viscosity, non-liquid crystalline,mixture of: a) at least one neutral diacyl lipid and/or at least onetocopherol; b) at least one phospholipid; c) at least one biocompatible,oxygen containing, low viscosity organic solvent; wherein at least onebioactive agent is dissolved or dispersed in the low viscosity mixtureand wherein the pre-formulation forms, or is capable of forming, atleast one liquid crystalline phase structure upon contact with anaqueous fluid.
 2. A pre-formulation as claimed in claim 1 wherein saidliquid crystalline phase structure is bioadhesive.
 3. A pre-formulationas claimed in claim 1 wherein component a) consists essentially ofdiacyl glycerols, especially glycerol dioleate.
 4. A pre-formulation asclaimed in claim 1 wherein component a) consists essentially of at leastone tocopherol.
 5. A pre-formulation as claimed in claim 1 whereincomponent a) consists essentially of a mixture of GDO and tocopherol. 6.A pre-formulation as claimed in claim 1 wherein component b) is selectedfrom phosphatidylcholines, phosphatidylethanolamines,phosphatidylserines, phosphatidylinositols and mixtures thereof.
 7. Apreformulation as claimed in claim 1 having a viscosity of 0.1 to 5000mPas.
 8. A preformulation as claimed in claim 1 having a molecularsolution, L2 and/or L3 phase structure.
 9. A preformulation as claimedin claim 1 having a ratio of a) to b) of between 95:5 and 5:95 byweight.
 10. A preformulation as claimed in claim 1 having 0.5 to 50%component c) by weight of components a)+b)+c).
 11. A preformulation asclaimed in claim 1 wherein component c) is selected from alcohols,ketones, esters, ethers, amides, sulphoxides and mixtures thereof.
 12. Apreformulation as claimed in claim 1 additionally comprising up to 10%by weight of a)+b) of a charged amphiphile.
 13. A preformulation asclaimed in claim 1 wherein said active agent is selected from drugs,antigens, nutrients, cosmetics, fragrances, flavourings, diagnosticagents, vitamins, dietary supplements and mixtures thereof.
 14. Apreformulation as claimed in claim 13 wherein said drugs is selectedfrom hydrophilic small molecule drugs, lipophilic small molecule drugs,amphiphilic small molecule drugs, peptides, proteins, oligonucleotidesand mixtures thereof.
 15. A preformulation as claimed in claim 13wherein said drug is selected from somatostatin related peptides,interferons, glucagon-like peptides 1 and 2, GnRH agonists, GnRHantagonists, bisphosphonates, chlorhexidine and mixtures thereof.
 16. Apreformulation as claimed in claim 1 which is administrable byinjection.
 17. A preformulation as claimed in claim 1 which isadministrable by spraying, dipping, rinsing, application from a pad orball roller, painting, dropping, aerosol spraying or pump spraying. 18.An injectable preformulation as claimed in claim 1 which forms a depotproviding continuous release of active agent for at least two weeks,wherein said active agent comprises at least one selected from i.octreotide ii. human growth hormone iii. interferon alpha iv. leuprolide19. An injectable preformulation as claimed in claim 1 which forms adepot providing continuous release of active agent for at least twoweeks, wherein said active agent comprises at least one selected from i.risperidone ii. olanzapine iii. testosterone undecanoate
 20. A topicalformulation as claimed in claim 1 for intraoral administration whichforms a bioadhesive, controlled release product, wherein said activeagent comprises at least one selected from i. benzydamine ii. tramadol21-37. (canceled)